Simplify skeleton requests, limit bor spanCache, more fine grained locking in HeaderDownload (#4194)

* Simplify skeleton requests

* Limit bor cache size

* In the middle of changing lists

* Fix

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>
Co-authored-by: Alex Sharp <alexsharp@Alexs-MacBook-Pro.local>

* Reduce insertQueue usage, throttle Skeleton requests

* Cleanup

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

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* Changes:
* Proceeded to check if other h, r, t or c flags for 'before' and 'older' are set before returning from the default state of --prune
Concern:
* Does the 'disabled' value for '--prune=' need to be updated if the '--prune.*' flags are set but the '--prune=' flag is not?

* Modify mode.Initialised only when it is changed

* Updated layout for --prune=*

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Co-authored-by: alex.sharov <AskAlexSharov@gmail.com>

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* Fix interaction with beacon node

* Fix logging

* Fix logging and add comments

* Fix logging

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

Co-authored-by: Alex Sharp <alexsharp@Alexs-MacBook-Pro.local>

* added check method to hd

* goroutine to check if we have headers

* added initial cycle to Ethereum object

* stage loop will only run ones

* got rid of anchor print

* header stage skip cycle message

* increased original time by a 2 seconds

* for inside of stageloop

* simplified

* little fixes

* got rid of skipCycle

* simplified

* hmm

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

* Further simplify header download, req/resp metrics

* Not break the loop

* Move anchors correctly

* Log anchor state

* Print minNum

* Print hash

* Always add links

* Remove obsolete test

* cleanup

Co-authored-by: Alex Sharp <alexsharp@Alexs-MacBook-Pro.local>
Co-authored-by: Alex Sharp <alexsharp@alexs-macbook-pro.home>

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RPCDaemon: open snapshots on startup (because now snapshots dir is atomic), even if no Erigon available (#4110)

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* Simplify header downloader

* Remove VerifyQueue

* Fix

* More fixes

* Fix

* Break out of the loop

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

Rename sentry.ControlServerImpl to sentry.MultyClient and sentry.SentryServerImpl to sentry.GrpcServer #444

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* atomic snapshot dir

* atomic snapshot dir

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

* penalize naughty peers

* lint

* Undo headers relaxation change

* Undo headers relaxation change

Co-authored-by: Alex Sharp <alexsharp@Alexs-MacBook-Pro.local>

* More relax inclusion of headers in the downloader

* Fix

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

* cmd/utils: initialize f.Value before setting variable

* override.terminaltotaldifficulty flag

* Add OverrideTerminalTotalDifficulty to default_flags

* reduce downloader deps

* reduce downloader deps

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* reduce downloader deps

* reduce downloader deps

* reduce downloader deps

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* Potential fix for verification

* multi verify

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>
Co-authored-by: Alex Sharp <alexsharp@Alexs-MacBook-Pro.local>