Dev mode for integration tests

[darwintree]

This change is 

[ChenxingLi]

Before we accept this PR, we need some experimental data to ensure it actually helps improve test speed.

Reviewable status: 0 of 14 files reviewed, all discussions resolved (waiting on @Pana)

[darwintree]

Before we accept this PR, we need some experimental data to ensure it actually helps improve test speed.

Reviewable status: 0 of 14 files reviewed, all discussions resolved (waiting on @Pana)

Here is part of the local test data (macOS, M2 PRO) for the result for the command pytest integration_tests/tests/execution_spec_tests -n 6 --dist loadscope:

before (in test mode): 829 passed, 904 warnings in 231.04s (0:03:51)
now (in dev mode): 829 passed, 904 warnings in 40.17s

And you can find the result in recent CI consoles:

Before(https://jenkins.conflux-chain.org.cn/job/conflux-rust/1359/console):

================ 1084 passed, 913 warnings in 327.92s (0:05:27) ================

This pr(https://jenkins.conflux-chain.org.cn/job/conflux-rust/1360/console):

================ 1084 passed, 913 warnings in 247.35s (0:04:07) ================

Turning a test containing lots of transaction sending would greatly accelerate it. But not all tests are suitable for dev mode so this pull request simply turns part of execution tests into dev mode