bgpd: compare aigp after local route check in bgp_path_info_cmp() (backport #17199)

[mergify]

For consistency between RIB and BGP, the aigp comparison should be made after the local route check in bgp bestpath selection.

As a reference, that's exactly what Cisco IOS does:

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/119001-configure-aigp-00.html

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This is an automatic backport of pull request #17199 done by Mergify.

[mergify]

Cherry-pick of 1a2c3d6 has failed:

On branch mergify/bp/stable/10.1/pr-17199
Your branch is up to date with 'origin/stable/10.1'.

You are currently cherry-picking commit 1a2c3d684a.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   tests/topotests/bgp_aigp_rr/r1/bgpd.conf
	deleted by us:   tests/topotests/bgp_aigp_rr/r2/bgpd.conf
	deleted by us:   tests/topotests/bgp_aigp_rr/test_bgp_aigp_rr.py

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[ton31337]

Created a manual backport here #17239, closing this.