RDKB-39452: Invalid character length is accepted in ULA prefix field
RDKB-39452: Invalid character length is accepted in ULA prefix field

Reason for change:
ULA prefix field validation is corrected

Test Procedure:
Navigate to Gateway - Connection - Local IP Network
 - Under IPv6 section, ULA Prefix should accept only valid addresses

Risks: Low
Signed-off-by: 2267bbc999fd2ec0e6ed9bde1645d9209c44b6cc@sky.uk
(cherry picked from commit 39f8e588e677f360f3176e356eca7a156fb49c80)
Change-Id: I9121716b558b641d5ef4a64f9550b2a39e03cd21

rdkcmf/rdkb-webui,rdkcmf/rdkb-webui,rdkcmf/rdkb-webui,rdkcmf/rdkb-webui,rdkcmf/rdkb-webui