Arista: allow standard community-list without standard keyword

[dhalperi]

This was parsed, but crashed in extraction.

[batfish-bot]

This change is 

[progwriter]

Reviewed 3 of 3 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved

[codecov]

Codecov Report

Merging #5582 into master will decrease coverage by <.01%.
The diff coverage is 50%.

@@             Coverage Diff              @@
##             master    #5582      +/-   ##
============================================
- Coverage     73.66%   73.65%   -0.01%     
+ Complexity    32562    32560       -2     
============================================
  Files          2651     2651              
  Lines        130300   130302       +2     
  Branches      15563    15564       +1     
============================================
- Hits          95984    95979       -5     
- Misses        26737    26742       +5     
- Partials       7579     7581       +2

Impacted Files	Coverage Δ	Complexity Δ
...fish/grammar/cisco/CiscoControlPlaneExtractor.java	67.61% <50%> (+0.01%)	1420 <0> (+1)	⬆️
...col/src/main/java/org/batfish/role/InferRoles.java	89.54% <0%> (-1.37%)	50% <0%> (-1%)
...src/main/java/org/batfish/coordinator/PoolMgr.java	64.04% <0%> (-1.13%)	15% <0%> (-1%)
...tfish/representation/cisco/CiscoConfiguration.java	86.09% <0%> (-0.12%)	548% <0%> (-1%)