chore: rewrite user-facing messages in Crm module

Conservative cleanup of frappe.throw/msgprint messages per the message style
guide; meaning, severity, and .format() arguments are unchanged:

- index bare {} placeholders as {0}/{1}/... so translators can reorder
- move f-strings / .format() / concatenation out of _() (they break gettext
  extraction and never translate)
- wrap translatable dynamic values (DocType/Select labels) in _()
- fix grammar and colloquialisms
- drop no-op _() wrapping runtime-built strings

Part of #53976.

erpnext/crm/doctype/appointment_booking_settings/appointment_booking_settings.py

@@ -59,7 +59,7 @@ class AppointmentBookingSettings(Document):
 			err_msg = _("<b>From Time</b> cannot be later than <b>To Time</b> for {0}").format(
 				record.day_of_week
 			)
-			frappe.throw(_(err_msg))
+			frappe.throw(err_msg)
 
 	def duration_is_divisible(self, from_time, to_time):
 		timedelta = to_time - from_time

erpnext/crm/doctype/crm_settings/crm_settings.py

@@ -49,7 +49,7 @@ class CRMSettings(Document):
 		if self.enable_frappe_crm_data_synchronization and not self.allowed_users:
 			frappe.throw(
 				_(
-					"Please add atleast one user on Allowed Users to allow Data Synchronization from Frappe CRM site."
+					"Please add at least one user on Allowed Users to allow Data Synchronization from Frappe CRM site."
 				)
 			)