Remove dead code in TLSX_PopulateExtensions() around MAX_PSK_ID_LEN check

[cconlon]

Description

Fixes dead code recently introduced with #8302. Caught by Coverity scan:

>>>     CID 445084:  Control flow issues  (DEADCODE)
>>>     Execution cannot reach the expression "sess->ticketLen > 1536" inside this statement: "if (isServer && sess->ticke...".
13784                     if (isServer && (sess->ticketLen > MAX_PSK_ID_LEN)) {
13785                         WOLFSSL_MSG("Session ticket length for PSK ext is too large");
13786                         return BUFFER_ERROR;
13787                     }

The given code block is inside the following condition, which means this will never be called on the server-side (isServer=true):

if (!isServer && IsAtLeastTLSv1_3(ssl->version)) {
...
}

Testing

Caught by Coverity scan. See PR #8302 for testing notes.

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation