Improve handling of deleted blocks

[priojeetpriyom]

What was the problem?

This PR resolves #1191

How was it solved?

• Pause indexing before block deletion and resume afterwards
• Schedule block deletion first and index later on fork
• Introduce backoff strategy for indexer jobs and increase attempts. This will help to reduce connector load when all calls are failing and reduce block deletion skip due because of failure to minimum.
• Throw error on delete block message processor error. So that it is reprocessed

How was it tested?

• Digital ocean droplets with pattern: priojeet-testnet-[1-4]-improve-handling-of-deleted-blocks

[codecov]

Codecov Report

Merging #1896 (ff7f435) into release/0.7.0 (20a0138) will increase coverage by 0.38%.
The diff coverage is 56.25%.

@@                Coverage Diff                @@
##           release/0.7.0    #1896      +/-   ##
=================================================
+ Coverage          66.62%   67.01%   +0.38%     
=================================================
  Files                298      298              
  Lines               5250     5254       +4     
  Branches             949      954       +5     
=================================================
+ Hits                3498     3521      +23     
+ Misses              1752     1733      -19     

Files	Coverage Δ
services/blockchain-connector/config.js	100.00% <100.00%> (ø)
...-indexer/shared/dataService/business/generators.js	75.00% <ø> (+28.57%)	⬆️
...ndexer/shared/dataService/business/transactions.js	27.52% <ø> (ø)
services/blockchain-indexer/shared/regex.js	100.00% <100.00%> (ø)
...teway/apis/http-version3/methods/blockchainApps.js	100.00% <ø> (ø)
...is/http-version3/methods/blockchainAppsMetaList.js	100.00% <ø> (ø)
...is/http-version3/methods/blockchainAppsMetadata.js	100.00% <ø> (ø)
...tp-version3/methods/blockchainAppsTokenMetadata.js	100.00% <ø> (ø)
services/gateway/shared/regex.js	100.00% <100.00%> (ø)
services/gateway/tests/constants/paramValidator.js	100.00% <ø> (ø)
... and 2 more

... and 3 files with indirect coverage changes

[nagdahimanshu]

LGTM 👍