(fix) Add regex anchors to SSN identifier format validation

The regex for the SSN identifier format was missing the anchors (^ and $),
which caused the validation to fail for identifiers that did not exactly
match the required format of one uppercase letter, followed by a dash and
exactly 7 digits (e.g., "A-0010902"). Without these anchors, the pattern
could match invalid formats like "X-A-1234567-Y" (extra characters), or
"A-123456789" (too many digits), leading to potential data quality issues.
This PR adds start and end anchors to ensure the identifier strictly follows
the required format. It also updates the regex description to be more
descriptive and accurate.

Author: denniskigen

configuration/backend_configuration/patientidentifiertypes/patientidentifiertypes-core_demo.csv

@@ -2,4 +2,4 @@ Uuid,Void/Retire,Name,Description,Required,Format,Format description,Validator,L
 05a29f94-c0ed-11e2-94be-8c13b969e334,,OpenMRS ID,"OpenMRS patient identifier, with check-digit",TRUE,,,org.openmrs.module.idgen.validator.LuhnMod30IdentifierValidator,NOT_USED,UNIQUE
 22348099-3873-459e-a32e-d93b17eda533,,Legacy ID,Identifier type to record optional previous identifers ,FALSE,,,,NOT_USED,
 b4143563-16cd-4439-b288-f83d61670fc8,,ID Card,ID Card,FALSE,,,,NOT_USED,UNIQUE
-a71403f3-8584-4289-ab41-2b4e5570bd45,,SSN,Social Security Number,FALSE,[A-Z]{1}-[0-9]{7},"Identifier should be 1 letter, followed by a dash and 7 numerical characters. Eg, A-0010902",,NOT_USED,UNIQUE
+a71403f3-8584-4289-ab41-2b4e5570bd45,,SSN,Social Security Number,FALSE,^[A-Z]{1}-[0-9]{7}$,"Identifier must be exactly one uppercase letter, followed by a dash and exactly 7 digits. Example: A-0010902",,NOT_USED,UNIQUE