Fix KeyError that occurred when formatting compact currencies of exactly one thousand in several locales

[bartbroere]

This fixes #1245 by adding a smoke test and falling back to the other rules for formatting numbers if the one rule is not there. See the original issue for more details.

To reproduce the original errors, you could run the smoke tests without the fix in babel.numbers:

# only check out the newly added tests, without the fix
git checkout 64465cc4cbf978715a527e343ea3c4ff6b0906c5
# run tox
python3 -m tox

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.04%. Comparing base (851db43) to head (7034ca1).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1246   +/-   ##
=======================================
  Coverage   92.04%   92.04%           
=======================================
  Files          27       27           
  Lines        4713     4715    +2     
=======================================
+ Hits         4338     4340    +2     
  Misses        375      375           

Flag	Coverage Δ
macos-14-3.10	91.09% <100.00%> (+<0.01%)	⬆️
macos-14-3.11	91.02% <100.00%> (+<0.01%)	⬆️
macos-14-3.12	91.24% <100.00%> (+<0.01%)	⬆️
macos-14-3.13	91.24% <100.00%> (+<0.01%)	⬆️
macos-14-3.14	91.21% <100.00%> (+<0.01%)	⬆️
macos-14-3.8	90.95% <100.00%> (+<0.01%)	⬆️
macos-14-3.9	91.02% <100.00%> (+<0.01%)	⬆️
macos-14-pypy3.10	91.09% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-3.10	91.11% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-3.11	91.04% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-3.12	91.26% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-3.13	91.26% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-3.14	91.24% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-3.8	90.98% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-3.9	91.04% <100.00%> (+<0.01%)	⬆️
ubuntu-24.04-pypy3.10	91.11% <100.00%> (+<0.01%)	⬆️
windows-2022-3.10	91.10% <100.00%> (+<0.01%)	⬆️
windows-2022-3.11	91.04% <100.00%> (+<0.01%)	⬆️
windows-2022-3.12	91.25% <100.00%> (+<0.01%)	⬆️
windows-2022-3.13	91.25% <100.00%> (+<0.01%)	⬆️
windows-2022-3.14	91.23% <100.00%> (+<0.01%)	⬆️
windows-2022-3.8	91.07% <100.00%> (+<0.01%)	⬆️
windows-2022-3.9	91.03% <100.00%> (+<0.01%)	⬆️
windows-2022-pypy3.10	91.10% <100.00%> (+<0.01%)	⬆️

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