Temporary fix for EP-678

[AlexTrotsenko]

Temporary disable bulk_get, which causes issues during the replication.

New hotfix 1.37.3 will be released with this change only (using EP-678_no-bulk-get-fix branch).

@gloushkov, for the new release 1.37.4 these changes need to be merged in the dev branch if no better solution found and the fix is still needed.

[AlexTrotsenko]

To keep things posted:

• the issue was on the server-side of the couch. It's related to the malformed http multi-part response in case when atts_since where specified, but no attachment was changed since specified revision.
• unless other is required for stability of all the system in general - we should not include this PR in the upcoming release. (You can always check with @AlexanderKaraberov if the server-side fix is ready)