Make count for numSyncsInProgress static

numSyncsInProgress is used to keep track of how many syncs VRI has
started to ensure it can disable RT Animations and then enable at the
end of the sync. This needs to be global across the process because RT
Animations config is global to the process. This means if there are any
VRI's in a sync across the process, we need to keep RT Animations
disabled until the end of all of them.

Test: Sync works
Bug: 237804605
Change-Id: I6304061f564ceea9de08331d7ee48834ad3c828b