Fix parse_usage_ping_keys method to test metrics with schemas

What does this MR do?

Related to #335532 (closed).

This modifies parsing Service Ping (formerly Usage Ping) in Every metric definition specs to stop and do not evaluate data structure inside metrics that have value_json_schema defined in their metric definitions. These can have various non-standard structures (including Arrays and keys that do not have their own metric definitions) and will fail the spec.

Instead, their structure is validated by a JSON Schema file, whose path is given in value_json_schema. topology and histograms are now supported by the specs and have been removed from the ignored key patterns.

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.