Currently, during the transition of jstests to the jsCore* suites we have more than one shell write mode being used:

• default: shell-write-mode = legacy
• gle: shell-write-mode = legacy
• jsCore*: shell-write-mode = commands/compatibility

The change would be to run with shell-write-mode of commands unless overridden by the suite explicitly, like for the gle suite.

In addition we need to change the "default" when no explicit shell-write-mode is specified as an argument to align to what is required for each suite/test.