Add more FCI L2 CRM and ASR datasets and fix warnings

[strandgren]

This PR fixes a couple of issues with the EUMETSAT FCI L2 readers:

• Add a couple of more ASR and CRM datasets (information on angles and cloud/clear-sky fractions)

• Remove use of get_legacy_chunk_size to determine chunk size, resolving Reading FCI L2 data yields warning on chunking performance #3321.

• Remove warning on missing projection longitude for AMV products which are not projected and thus not expected to have the projection longitude information available.

• Closes Reading FCI L2 data yields warning on chunking performance #3321

• Tests adapted

[pnuu]

LGTM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.32%. Comparing base (6e92fc3) to head (862ea7c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3394   +/-   ##
=======================================
  Coverage   96.32%   96.32%           
=======================================
  Files         466      466           
  Lines       59090    59094    +4     
=======================================
+ Hits        56916    56920    +4     
  Misses       2174     2174           

Flag	Coverage Δ
behaviourtests	3.59% <0.00%> (-0.01%)	⬇️
unittests	96.41% <100.00%> (+<0.01%)	⬆️

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