cli: use "_ALL_PROVIDERS" as for provider options

[rpjday]

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[codecov-commenter]

Codecov Report

Merging #4308 (289b00f) into main (9a681aa) will decrease coverage by 0.02%.
The diff coverage is n/a.

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@@            Coverage Diff             @@
##             main    #4308      +/-   ##
==========================================
- Coverage   89.08%   89.06%   -0.02%     
==========================================
  Files         300      299       -1     
  Lines       20571    20530      -41     
==========================================
- Hits        18325    18285      -40     
+ Misses       2246     2245       -1     

Files Changed	Coverage Δ
snapcraft_legacy/cli/_options.py	85.31% <ø> (ø)

... and 3 files with indirect coverage changes

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