DPE-6662 Fix pgbackrest logs names on logs rotation (#939)

[taurus-forever]

Backport #939 to PG14.

The pgBackRest activity (backup creation, stanza initialisation, etc) could take minutes, as a result every minute logs rotation could move the current log A.log to A.log_$date.log and will be moved further as logrorate rule operates all *.log files in the folder:

/var/snap/charmed-postgresql/common/var/log/pgbackrest/*.log { ...

It results in:

-rw------- 1 postgres postgres 0 Feb 18 09:25 all-server.log
-rw------- 1 postgres postgres 0 Feb 18 09:19 all-server.log-20250218_09:18.log
-rw------- 1 postgres postgres 0 Feb 18 09:20 all-server.log-20250218_09:18.log-20250218_09:19.log
-rw------- 1 postgres postgres 0 Feb 18 09:21 all-server.log-20250218_09:18.log-20250218_09:19.log-20250218_09:20.log
-rw------- 1 postgres postgres 0 Feb 18 09:22 all-server.log-20250218_09:18.log-20250218_09:19.log-20250218_09:20.log-20250218_09:21.log
-rw------- 1 postgres postgres 0 Feb 18 09:23 all-server.log-20250218_09:18.log-20250218_09:19.log-20250218_09:20.log-20250218_09:21.log-20250218_09:22.log
-rw------- 1 postgres postgres 1793 Feb 18 09:24 all-server.log-20250218_09:18.log-20250218_09:19.log-20250218_09:20.log-20250218_09:21.log-20250218_09:22.log-20250218_09:23.log

The poposed fix:

• move the log file to the new name without .log suffix.
• use datetime format matching MySQL charms

Example:

-rw------- 1 postgres postgres 12 Feb 18 09:28 all-server.log
-rw------- 1 postgres postgres 322 Feb 18 09:29 all-server.log-20250218_0918
-rw------- 1 postgres postgres 7344 Feb 18 09:30 all-server.log-20250218_0918

(cherry picked from commit ffa77b2)

Issue

Solution

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.76%. Comparing base (2296dca) to head (0bbdc1f).
Report is 3 commits behind head on main.

Additional details and impacted files

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  Coverage   71.76%   71.76%           
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  Files          16       16           
  Lines        4101     4101           
  Branches      617      617           
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  Hits         2943     2943           
  Misses        964      964           
  Partials      194      194           

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