More sensible client meta operation timeout default

Documented behavior in the HBase reference for client meta operation timeout hbase.client.meta.operation.timeout default is that it will be set to the configured client operation timeout, but implementation is that it defaults to the default client operation timeout of 20 minutes. I propose to set the default meta operation to what is currently specified in the hbase reference: 

From "Timeout settings" in the hbase reference:

There seem to be two very different dependencies on meta operation timeout:

1. End to end operation timeout for system table operations (2.x and 3)
2. Timeout to acquire userRegionLock to initiate meta scan in locateRegionInMeta (2.x blocking client only, see HBASE-28730 for more detail/related work)

For case 1 I believe it makes sense from a user perspective that meta operation timeout, which is meant to apply to a specific subset of operations, will respect the 'general' operation timeout that is configured if the more specific meta operation timeout is not explicitly set. 

For case 2 blocking client, the default meta timeout value defeats the purpose of the `userRegionLock` timeout if one has a typical setup where hbase.client.operation.timeout << 20 minutes and hbase.client.meta.operation.timeout is not explicitly set, which can lead to operations taking much longer than the configured operation timeout to actually timeout if there is e.g meta slowness and/or contention around userRegionLock on 2.x, see HBASE-28730 for more detail/related work.