[SYNC] Clean up num_encryption_conflicts.

Remove num_encryption_conflicts of ModelNeutralState.

Bug: 1315573
Change-Id: I58b17f1f2181354b1927eb49f74d344b7a8d31d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3626732


Commit-Queue: Rushan Suleymanov <rushans@google.com>
Auto-Submit: qian zhuoyu <zhuoyuqian@microsoft.com>
Reviewed-by: Rushan Suleymanov <rushans@google.com>
Cr-Commit-Position: refs/heads/main@{#999775}