When syncing with client: always full recheck on Google Drive mounts

Referencing: https://github.com/owncloud/client/issues/8035

Steps to reproduce

1. create a GD mount and put many files in
2. let the client sync that mount
3. watch the client regulary

Expected behaviour

Check for changed files only

Actual behaviour

Full recheck when syncing with GD mounts.
Having local, SMB and GD mounts. Only on GD, the client does a full check which takes a while.
I may be wrong, but this has to do with 10.5, because this was not the case up to 10.4.x
It was quick on GD before, but now it looks like it always does a full check on every file.
Maybe this is optical recognizable, as GD is much slower than local and SMB, but is is apparrent

Impact: having lots of GD mounts/files can lead to a very long sync-check

Server configuration

Operating system: Ubuntu 18.04

Web server: nginx

Database: mariadb

PHP version: 7.3

ownCloud version: 10.5

Updated from an older ownCloud or fresh install: updated

Where did you install ownCloud from: tar

Signing status (ownCloud 9.0 and above): all ok

Are you using external storage, if yes which one: local/smb/gd/

Are you using encryption: no

Client configuration

Browser: opera

Operating system: W10x64

Sync Client configuration

Client: 2.6.3

@michaelstingl fyi

Start by reviewing the referenced issue 8035 and reproducing the behavior with ownCloud 10.5 and client 2.6.3 using local, SMB, and Google Drive mounts. Compare sync checks for changed files against the full recheck described in the report; done means Google Drive mounts no longer perform a full check on every sync.