mysql2 - migrate to v3 in tests

[blumamir]

renovate opened up #2095 to upgrade mysql2 package to a new version 3.

While we only use it for tests, the security warning is not a concern for us, but the tests are not compiling with the new version as a dev dependency:

> @opentelemetry/[email protected] compile
> tsc -p .

test/mysql.test.ts:145:29 - error TS2769: No overload matches this call.
  Overload 1 of 3, '(group: string, connectionUri: string): void', gave the following error.
    Argument of type 'PoolClusterOptions' is not assignable to parameter of type 'string'.
  Overload 2 of 3, '(group: string, config: PoolOptions): void', gave the following error.
    Type 'PoolClusterOptions' has no properties in common with type 'PoolOptions'.

145     poolCluster.add('name', {
                                ~
146       port,
    ~~~~~~~~~~~
... 
150       database,
    ~~~~~~~~~~~~~~~
151     } as mysqlTypes.PoolClusterOptions);
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Found 1 error.

npm ERR! Lifecycle script `compile` failed with error: 
npm ERR! Error: command failed 
npm ERR!   in workspace: @opentelemetry/[email protected] 
npm ERR!   at location: /Users/amirblum/repos/opentelemetry-js-contrib/plugins/node/opentelemetry-instrumentation-mysql2 

Not sure how tav is working properly.

In npm, seems that version 3 is the popular version, and v2 has security issues. So it does make sense to use the new version in instrumentation testing by default.

This issue closes #2095 which cannot merge, to track the task of upgrading the dev dependency to a more relevant version