Change "Wait for Sync" to "Not Now"

[houjoe0829]

Since there is no automatic process of signing out after the synchronization is completed after clicking "Wait for Sync", it should be changed to the simpler copywriting "Not Now".

[tzhangchi]

@DiamondThree could you get the improvement reason

[tzhangchi]

@joebeijing it's the same with #791

[DiamondThree]

Closed by #886