SwitchTraffic should switch everything when no tablet_types provided

[mattlord]

Description

The default --tablet_types value for the SwitchTraffic command was errantly changed in #10040 where we generally made in_order:REPLICA,PRIMARY the default --tablet_types value in VReplication. For SwitchTraffic, we should be switching traffic for all tablet types when none are specified: https://vitess.io/docs/14.0/reference/vreplication/switchtraffic/#--tablet_types

⚠️ After further testing, however, it became clear that we never handled SwitchedTraffic for RDONLY tablets when no value was specified for --tablet_types. That's because the flag has a default value so it was never an empty string here and the override was never applied (before or after changing what we overrode it to). From v13:

vitess/go/vt/vtctl/vtctl.go

Lines 2443 to 2448 in 12fc1f0

	case vReplicationWorkflowActionSwitchTraffic, vReplicationWorkflowActionReverseTraffic:
	vrwp.Cells = *cells
	vrwp.TabletTypes = *tabletTypes
	if vrwp.TabletTypes == "" {
	vrwp.TabletTypes = "primary,replica,rdonly"
	}

So, in this PR we do the following:

1. Check if the --tablet_types flag was passed on the command line, and if not then we use the new override to switch everything by default
2. Updated the endtoend test so that it explicitly tests the behavior when no --tablet_flag value was provided on the command-line when we intend to switch all traffic
3. Added to the endtoend tests so that we are using RDONLY tablets and confirm that traffic for them is also switched when doing SwitchTraffic w/o a --tablet_types flag value

I will also update the v14 docs to the new default here of: in_order:RDONLY,REPLICA,PRIMARY

Related Issue(s)

• Fixes: Bug Report: vtctlclient MoveTables SwitchTraffic doesnt switch readonly traffic #10421
• Follow-up to: Prefer using REPLICA tablets when selecting vreplication sources #10040

Checklist

• "Backport me!" label has been added if this change should be backported
• Tests were updated
• Documentation: Update SwitchWrites tablet_types default website#1044

[github-actions]

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[rohit-nayak-ps]

❤️

[rohit-nayak-ps]

lgtm
nice catch

[mattlord]

Manual test to confirm fix for #10421:

$ cd examples/local

$ ./101_initial_cluster.sh ; ./201_customer_tablets.sh ; ./202_move_tables.sh

$ vtctlclient --server=localhost:15999 MoveTables SwitchTraffic customer.commerce2customer
SwitchTraffic was successful for workflow customer.commerce2customer
Start State: Reads Not Switched. Writes Not Switched
Current State: All Reads Switched. Writes Switched