[LLDP][T2] Advertise Chassis Hostname when present.

[abdosi]

Why I did:
For chassis Advertise Chassis Hostname instead of Line Card Hostname if available to LLDP peers.

• Yang Change for Chassis Hostname: [chassis] add chassis hostname to device metadata #19019
• Minigraph Change for parsing Chassis Hostname: https://github.com/sonic-net/sonic-buildimage/pull/19018/files#diff-466ae5de99730b4f3dde9c932e9086536e3a0226858c735fbf776453e8d86fafR2127

How I did:

Prefer Chasiss hostname if available over Local Hostname.

How I verify:
Manual Testing.

[abdosi]

/azpw ms_conflict'

[zhangyanzhao]

code PRs are merged and mark this as done for 202405 release.

[rajann]

Could you please cheery pick this PR to 202311 branch as well