flask: fixed http_server_request_duration metrics being recorded for excluded urls

[rads-1996]

Fixed an issue #2352 where http_server_request_duration metrics was being recorded for excluded urls.

Description

Fixes #2352

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• A flask application was set up using the reproduction steps outlined in the linked issue, and the before-and-after changes have been captured and attached to the PR.
• Modified existing unit tests to conform to new functionality

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[rads-1996]

In the current scenario, when requests are made to the excluded /health endpoint, each hit is recorded as a failed request. For this instance, 7 requests were made to the /health endpoint -

After the change, server request duration metrics are recorded only for non-excluded URLs. In this case, 3 requests were made to the /health endpoint -