openapi3: collapse repeated combinator scope in nested allOf/anyOf/oneOf

SchemaCombinatorElementValidationError wraps each combinator element, so a
deeply nested same-combinator schema (common in the AWS specs) rendered
"invalid allOf element: " once per nesting level. Collapse a run of
same-combinator wrappers in Error() so the scope prints once. The typed chain
is unchanged: Unwrap and errors.As still see every level, only the rendered
message drops the repeats, and a run of a different combinator (e.g. allOf
inside a oneOf) is still shown.

Adds a wrapper test for the collapse and chain preservation, and regenerates
the affected apis-guru goldens.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: reuvenharrison

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_application_autoscaling_2016_02_06_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "DescribeScalingPoliciesResponse": invalid allOf element: invalid allOf element: error parsing regexp: invalid character class range: `\p{Print}`
+invalid components: schema "DescribeScalingPoliciesResponse": invalid allOf element: error parsing regexp: invalid character class range: `\p{Print}`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_applicationcostprofiler_2020_09_10_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "GetReportDefinitionResult": invalid allOf element: invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?=`
+invalid components: schema "GetReportDefinitionResult": invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?=`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_codecatalyst_2022_09_28_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "CreateDevEnvironmentRequest": invalid allOf element: invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`
+invalid components: schema "CreateDevEnvironmentRequest": invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_cognito_idp_2016_04_18_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "DescribeUserPoolDomainResponse": invalid allOf element: invalid allOf element: error parsing regexp: invalid named capture: `(?<!\.)$`
+invalid components: schema "DescribeUserPoolDomainResponse": invalid allOf element: error parsing regexp: invalid named capture: `(?<!\.)$`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_comprehend_2017_11_27_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "CreateEntityRecognizerRequest": invalid allOf element: invalid allOf element: invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`
+invalid components: schema "CreateEntityRecognizerRequest": invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_comprehendmedical_2018_10_30_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "ComprehendMedicalAsyncJobProperties": invalid allOf element: invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`
+invalid components: schema "ComprehendMedicalAsyncJobProperties": invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_datasync_2018_11_09_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "AddStorageSystemRequest": invalid allOf element: invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`
+invalid components: schema "AddStorageSystemRequest": invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_dlm_2018_01_12_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "CreateLifecyclePolicyRequest": invalid allOf element: invalid allOf element: invalid allOf element: invalid allOf element: error parsing regexp: invalid character class range: `\p{all}`
+invalid components: schema "CreateLifecyclePolicyRequest": invalid allOf element: error parsing regexp: invalid character class range: `\p{all}`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_elasticfilesystem_2015_02_01_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "AccessPointDescription": invalid allOf element: invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`
+invalid components: schema "AccessPointDescription": invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`

openapi3/testdata/apis_guru_openapi_directory/amazonaws_com_finspace_2021_03_12_openapi_yaml__validate

@@ -1 +1 @@
-invalid components: schema "CreateKxClusterRequest": invalid allOf element: invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`
+invalid components: schema "CreateKxClusterRequest": invalid allOf element: error parsing regexp: invalid or unsupported Perl syntax: `(?!`