chore: increase the cutover lock timeout

[d-bytebase]

A Pull Request should be associated with an Issue.

We wish to have discussions in Issues. A single issue may be targeted by multiple PRs. If you're offering a new feature or fixing anything, we'd like to know beforehand in Issues, and potentially we'll be able to point development in a particular direction.

Related issue: https://github.com/github/gh-ost/issues/0123456789

Further notes in https://github.com/github/gh-ost/blob/master/.github/CONTRIBUTING.md Thank you! We are open to PRs, but please understand if for technical reasons we are unable to accept each and any PR

Description

The maximum 10-second timeout is almost never gonna make gh-ost to work for large tables. We should give control to users for this flag.

In case this PR introduced Go code changes:

• [x] contributed code is using same conventions as original code
• [X] script/cibuild returns with no formatting errors, build errors or unit test errors.