fix: use estimated gas rate for bitcoin outTx and put a cap on total fee

[ws4charlie]

Description

We paid up to 3M satoshis ($800) in mock mainnet for bitcoin outTx which is way more than enough. A more reasonable gas price needs to be used.

1. Use estimated fee rate to send bitcoin outTx.
2. Put 0.001 BTC as the cap of fee. (in case of accident)
3. Round gas price to multiple of 1000 satoshis across TSS signers.

Closes:

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Include instructions and any relevant details so others can reproduce.

• Tested CCTX in localnet
• Tested in development environment
• Go unit tests
• Go integration tests
• Tested via GitHub Actions

Checklist:

• I have added unit tests that prove my fix feature works

[github-actions]

!!!WARNING!!!
nosec detected in the following files: zetaclient/bitcoin_client.go, zetaclient/btc_signer.go

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[lumtis]

Is it still relevant @ws4charlie or does #1243 replaces it?

[lumtis]

Closing, please feel free to reopen