prevent nginx failing on duplicated configuration lines

[webavant]

Description

Fixes issues:

• Un-tracked issue: nginx update script creating duplicate server_tokens in nginx's configuration directives is causing nginx service failure on start

Proposed Changes:

• change behavior to only add server_tokens directive when no match found (rather than when fewer than two matches are found) in nginx config file

Change Categories

• Bug fix

Checklist

• Branch was made off the develop branch and the PR is targetting the develop branch
• Docs have been made OR are not necessary
  • PR link:
• Changes to panel have been made OR are not necessary
  • PR link:
• Code conforms to project structure (See more)
• Prints to terminal are handled (See more)
• I have commented my code, particularly in hard-to-understand areas
• Testing was done
  • Tests created or no new tests necessary
  • Tests executed

Test scenarios

Ran shellcheck scripts/update/nginx.sh without any new errors/warnings

Architectures

	amd64	armhf	arm64	Unspecified
Jammy
Focal
Bookworm
Bullseye
Buster
Raspbian	⚫️		⚫️	⚫️

✅❎ Passed

🛠🛠 TODO

❌❌ Currently failing