chore: credentials pointing to mysql8 container

[farhanumar]

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Pointing of credentials to mysql8 container.

I've completed each of the following or determined they are not applicable:

• Made a plan to communicate any major developer interface changes (or N/A)

[adzuci]

@farhanumar I see many tests are failing for this PR, could you sync with Nadeem to see if we may be able to resolve some of the failures?

I think it may also be worth working with @justinhynes to ask what data devstack users have in the mysql5.7 containers and create a make command to copy that data into mysql 8 for when this PR is eventually moved. I think it may also be worth not merging this until we can do all services at once, adding a change log entry and possibly making some check to detect when devstack is launched for the first time on mysql8 so that we can make the migration smoother for devs.

[farhanumar]

@adzuci I had investigated these failures and fixed them here #1094, mysql57 has been hard-coded in some of the container images. I left it because this was something teams should fix it while they will be testing apps with mysql 8. The fix is easy see matt comment in #1094, mysql57 , its a string replacement in running container.

[adzuci]

That makes sense to me, could you update the PR description to include a note about that and describe the next steps for moving this work forward?