Refactor TestGasPriceIncrease ; Add Test Case

[axelKingsley]

@mslipper recently changed behavior in the Tx Manager, and I realized there was an opportunity to add testing around it.

• Added a txMod func to the existing tests, which modifies the transaction prior to increasing the gas
• used a No-Op modification in all test cases, except for...
• the new Test case which I added, injects inflated gas prices into the original transaction, and confirms that the original value is the one that gets used.
• I also reorganized the other tests, as I noticed that if the increase ever fails, err is the last thing that gets checked, meaning you'll end up hitting a null pointer on the other checks first.

[semgrep-app]

Semgrep found 6 golang_fmt_errorf_no_params findings:

• op-chain-ops/deployer/state/intent.go
  • L75 - Triage
• op-chain-ops/deployer/bootstrap/bootstrap.go
  • L41 - Triage
  • L45 - Triage
  • L55 - Triage
  • L59 - Triage
  • L63 - Triage

No fmt.Errorf invocations without fmt arguments allowed

_{Ignore this finding from golang_fmt_errorf_no_params.}