fix: prometheus could not be disabled

[yangby-cryptape]

What this PR does / why we need it?

This PR fixes:

• The server of prometheus could not be disabled.
• High security risk since the default address of prometheus is unspecified address.
• Should not use unwrap() since the address could be not provided.
• Cause errors for CI checks of multi-nodes. (ref: an example).
  • The configuration files for the multi-nodes test in CI haven't set prometheus section.
    So, all nodes use the default address. Then an error is caused: "Address already in use (os error 98)".

What is the impact of this PR?

No Breaking Change

CI Settings

CI Usage

Tip: Check the CI you want to run below, and then comment /run-ci.

CI Switch

• Cargo Clippy
• Coverage Test
• E2E Tests
• Code Format
• Unit Tests
• Web3 Compatible Tests
• OCT 1-5 And 12-15
• OCT 6-10
• OCT 11
• OCT 16-19
• v3 Core Tests

CI Description

CI Name	Description
Chaos CI	Test the liveness and robustness of Axon under terrible network condition
Cargo Clippy	Run cargo clippy --all --all-targets --all-features
Coverage Test	Get the unit test coverage report
E2E Test	Run end-to-end test to check interfaces
Code Format	Run cargo +nightly fmt --all -- --check and cargo sort -gwc
Web3 Compatible Test	Test the Web3 compatibility of Axon
v3 Core Test	Run the compatibility tests provided by Uniswap V3
OCT 1-5 | 6-10 | 11 | 12-15 | 16-19	Run the compatibility tests provided by OpenZeppelin