Sets sys-proctable smaps to false and parses stat directly for start times

What does this MR do?

This MR (hopefully) addresses the performance issues described in #61964 (closed). It does this by turning off smap parsing for the sys-proctable gem as described in https://github.com/djberg96/sys-proctable/issues/64. It also makes it so we parse /proc/self/stat directly to obtain process start times instead of parsing the whole proc table via the sys-proctable gem.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

If possible, I'd like some guidance on how we can properly test this to ensure that it does indeed fix the performance issues we were seeing in prod.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #61964 (closed)