[fix][broker] Fix web tls url null cause NPE

[Technoboy-]

Motivation

Related to #20535, if the web tls url is null, it will cause NPE:

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[codecov-commenter]

Codecov Report

Merging #21137 (b84f811) into master (c675a3d) will increase coverage by 39.83%.
Report is 1 commits behind head on master.
The diff coverage is 74.07%.

@@              Coverage Diff              @@
##             master   #21137       +/-   ##
=============================================
+ Coverage     33.37%   73.21%   +39.83%     
- Complexity    12158    32453    +20295     
=============================================
  Files          1623     1887      +264     
  Lines        127410   140004    +12594     
  Branches      13933    15423     +1490     
=============================================
+ Hits          42527   102504    +59977     
+ Misses        79258    29412    -49846     
- Partials       5625     8088     +2463     

Flag	Coverage Δ
inttests	24.16% <0.00%> (+0.10%)	⬆️
systests	25.11% <0.00%> (?)
unittests	72.48% <74.07%> (+40.58%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
...java/org/apache/pulsar/broker/rest/TopicsBase.java	58.31% <50.00%> (+58.31%)	⬆️
.../apache/pulsar/proxy/server/AdminProxyHandler.java	73.49% <80.95%> (+23.49%)	⬆️

... and 1531 files with indirect coverage changes