Initial Python 3.11 Cutover (SYN-4788, SYN-5095, SYN-5308)

[vEpiphyte]

• Build base synapse containers with debian bookworm / python 3.11
• Remove synapse/tests/files/certdir from images
• Update docker documentation to note PEP668 changes.

[codecov]

Codecov Report

Patch coverage: 50.00% and project coverage change: -12.07 ⚠️

Comparison is base (d487334) 97.29% compared to head (c949681) 85.23%.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #3025       +/-   ##
===========================================
- Coverage   97.29%   85.23%   -12.07%     
===========================================
  Files         222      222               
  Lines       44192    44200        +8     
===========================================
- Hits        42998    37673     -5325     
- Misses       1194     6527     +5333     

Flag	Coverage Δ
linux	85.23% <50.00%> (-11.97%)	⬇️
linux_replay	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
synapse/tests/utils.py	80.30% <50.00%> (-16.10%)	⬇️

... and 78 files with indirect coverage changes

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