Bump prometheus-client-mmap to 14.0 [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

The primary goal is to resolve #339001 (closed) - drop noisy warning polluting the output on Ruby 3 branch. It was fixed in https://gitlab.com/gitlab-org/prometheus-client-mmap/-/merge_requests/59 and included in 14.0 version of the gem.

Changelog:

v0.14.0
Remove deprecated taint mechanism logic

v0.13.0
Gauge: add decrement method to gauge metric type !57
Update push.rb to use newest client_ruby code !56994

How to setup and validate locally (strongly suggested)

1. Check: metrics are being collected when running on this branch
2. Additionally, when running with Ruby 3 (including specs), you should no longer see the warning: lib/prometheus/client/helper/entry_parser.rb:16: warning: Object#tainted? is deprecated and will be removed in Ruby 3.2. You will see them on older version of the gem, e.g. 0.13. Note: similar warning would still be appear coming fast-gettext, we are trying to resolve it upstream.

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.

Security

N/A

Related to #339001 (closed)