update helm chart to remove deprecated value to new value

[latoyalittlejohn]

This came up in ticket 106261:

pod:
  # -- Deprecated, use `serviceAccount.name` instead
  serviceAccountName: ""

Can update the chart to use serviceAccount.name instead just the comment?

helm/charts/rstudio-pm/values.yaml

Lines 119 to 120 in edc1399

	# -- Deprecated, use `serviceAccount.name` instead
	serviceAccountName: ""