Remove restriction on password length and bump go-mysql to 1.11.0

[joshvarner]

Related issue: #1524

Description

In prior versions of go-mysql, the actual password was used for the report-password portion of COM_REGISTER_SLAVE. This has two negative side effects:

1. The password is shown plaintext in the output of SHOW REPLICAS on the source that was connected to (if show-replica-auth-info=on on the source)
2. The password length is limited to <=32 characters

We should update to a newer version of go-mysql that now removes this erroneous behavior and also remove our restriction on password length, since it will no longer apply.

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

[meiji163]

If the password length limit is irrelevant now we should remove localtests/fail-password-length

[joshvarner]

If the password length limit is irrelevant now we should remove localtests/fail-password-length

Apologies for not catching this earlier-- the localtests mechanism wasn't super straightforward to me so I had not run them yet.