[DPE-6678] PostgreSQL Config Improvement

[Pepsiqqq]

This is copy of K8s PR, however there is an issue that PostgreSQL stucks in Awaiting for member to start. I think it's related to this issue because there is the same error (Failed to list PostgreSQL database users: could not translate host name "None" to address: Temporary failure in name resolution). On K8s side everything works as intended.

Added all missing parameters from PostgreSQL config analysis (Added params 25.05):
https://docs.google.com/spreadsheets/d/1CbJMmSSP5eyu08y5vM8RNGrjiSxOLsa7RelwwUsi-vg/edit?pli=1&gid=815242942#gid=815242942

Were not added:

1. client_encoding: Session only parameter that can't be set by Patroni. Source
2. transaction_deferrable: This parameter cannot be set in the configuration file, or from any source other than live SQL. Source
3. transaction_isolation: This parameter cannot be set in the configuration file, or from any source other than live SQL. Source
4. transaction_read_only: This parameter cannot be set in the configuration file, or from any source other than live SQL. Source

Notice:

1. old_snapshot_threshold: Will be deleted in 17 version. Source
2. default_table_access_method: Added dynamic validation.

Also sorted config to improve readability.

[codecov]

Codecov Report

Attention: Patch coverage is 75.11962% with 104 lines in your changes missing coverage. Please review.

Project coverage is 72.11%. Comparing base (5a7defe) to head (b42d59d).

Files with missing lines	Patch %	Lines
src/config.py	75.48%	51 Missing and 51 partials ⚠️
src/charm.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #778      +/-   ##
==========================================
+ Coverage   71.97%   72.11%   +0.13%     
==========================================
  Files          15       15              
  Lines        3479     3862     +383     
  Branches      532      583      +51     
==========================================
+ Hits         2504     2785     +281     
- Misses        845      897      +52     
- Partials      130      180      +50     

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[dragomirp]

Hi, @Pepsiqqq, please sync up with main, it should skip the tests that cannot run on forks.