junos: add route-level community lab for static, aggregate, and generate routes

[dhalperi]

Two-node vJunos-router lab testing which community forms Junos accepts
in routing-options {static|aggregate|generate} at route and
defaults level, and what the eBGP peer receives. Juniper's
community (Routing Options) reference describes large communities as
static-only; on 25.4R1.12 they are accepted in all six contexts and
reach the peer. Extended communities (target:, origin:) are
rejected by the CLI parser in all six. A DEFAULTS virtual-router
exercises the defaults blocks over a second eBGP session.

Batfish drops aggregate/generate routes carrying a route-level large
community and ignores large communities in their defaults blocks;
test_main_rib_routes and test_bgp_rib_routes are sickbayed against
batfish/batfish#10367.

lab_builder: _junos_commit_check now treats an error: response to a
set line as a rejection. Previously the rejected line was never
loaded, so commit check passed and the check reported "accepted".

Junos BGP parser: strip the Aggregator: line that aggregate routes
append to the as-path field.

---

Prompt:

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/community-edit-routing-options.html confuses me. It says that extended communities are not supported on static routes, and that large communities are ONLY supported on static routes. Can you build minimal Junos BGP labs to test this out?

Follow-up: extend the lab to exercise defaults with large
communities and what the peer receives, as a regression test.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.59%. Comparing base (feb209c) to head (206a4a9).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #235   +/-   ##
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  Coverage   83.58%   83.59%           
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  Files          96       96           
  Lines        4703     4705    +2     
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+ Hits         3931     3933    +2     
  Misses        772      772           

Flag	Coverage Δ
unittests	83.59% <100.00%> (+<0.01%)	⬆️

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