Remove `personal` namespace support and tests

[fselmo]

What was wrong?

• go-ethereum personal namespace is now deprecated as of v1.11.0. We should sunset the test suite and look into how this will shape the test suite overall.

How can it be fixed?

• Remove personal namespace and testing.
• drop rpc.enablepersonal flag from geth args when starting geth for fixtures.
• Investigate what sort of support may make sense for Clef, if any, and how this will affect the tests moving forward.