Fix failure during manifest setup

[DimaStebaev]

• resolve promises
• fix manifest filename
• remove manifest manipulations from mainnet upgrade script

Resolves #1612

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (2b7ef7d) 85.79% compared to head (3d686df) 85.79%.

:exclamation: Current head 3d686df differs from pull request most recent head 31c4710. Consider uploading reports for the commit 31c4710 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## v2.1.0 #1650 +/- ## ======================================= Coverage 85.79% 85.79% ======================================= Files 26 26 Lines 1464 1464 Branches 401 401 ======================================= Hits 1256 1256 Misses 33 33 Partials 175 175 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.