Use subscription at rejectIfBlockTimeout when the provider supports subscription

[Muhammad-Altabba]

Description

Implements #5467. In addition to a few code enhancements at tests.

However, because having lots of subscriptions and the tests are running in parallel some other issues showed up: #5517 and #5519 (and a related suggestion is interduced at #5521). And so this MR introduced a new config variable called enableExperimentalFeatures that contains useSubscriptionWhenCheckingBlockTimeout and the logic of this MR will run only when enableExperimentalFeatures.useSubscriptionWhenCheckingBlockTimeout is true. And tests are written for this accordingly.

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)

Checklist for 1.x:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run dtslint with success and extended the tests and types if necessary.
• I ran npm run test:cov and my test cases cover all the lines and branches of the added code.
• I ran npm run build with success.
• I have tested the built dist/web3.min.js in a browser.
• I have tested my code on the live network.
• I have checked the Deploy Preview and it looks correct.
• I have updated the CHANGELOG.md file in the root folder.

Checklist for 4.x:

• I have selected the correct 4.x base branch.
• Within the description, the feature or issue is discussed in detail or an issue is linked.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas.
• I have added any required tests for the changes I made
• I have made corresponding changes to the documentation
• Any dependent changes have been merged and published in downstream modules.
• I ran yarn successfully
• I ran yarn lint successfully
• I ran yarn build:web successfully
• I ran yarn test:unit successfully
• I ran yarn test:integration successfully
• I ran compile:contracts successfully
• I have tested my code.
• I have updated the corresponding CHANGELOG.md file in the packages I have edited.

[avkos]

some tests stuck (360m)

[Muhammad-Altabba]

some tests stuck (360m)

Those tests were not related to this MR. And they pass now after merging with the newest 4.x, as they are fixed and merged separately in different MRs.