Only log link state change events and setup counters post initialization
Only log link state change events and setup counters post initialization

Summary:
As titled, this was causing a crash on rsw1nf.17.prn1 (wedge100)
during agent restarts

Reviewed By: aeckert

Differential Revision: D3079690

fb-gh-sync-id: 8bc0f66cd223df1d8eba770bcb9e16a0be35058d
fbshipit-source-id: 8bc0f66cd223df1d8eba770bcb9e16a0be35058d

neuhausler/fboss,neuhausler/fboss,peterlei/fboss,neuhausler/fboss,peterlei/fboss,peterlei/fboss,neuhausler/fboss,peterlei/fboss