[improve][broker] Only get consumer future when interceptor not null

[michaeljmarshall]

Motivation

Builds on #18997. Essentially, we shouldn't get the consumer future when there isn't a broker interceptor.

Modifications

• Move the conditional check for brokerInterceptor != null earlier to prevent unnecessary work.

Verifying this change

This is a trivial change.

Documentation

• doc-not-needed

[codecov-commenter]

Codecov Report

Merging #19022 (af2af2f) into master (08591d9) will decrease coverage by 2.73%.
The diff coverage is 58.82%.

@@             Coverage Diff              @@
##             master   #19022      +/-   ##
============================================
- Coverage     49.85%   47.12%   -2.74%     
- Complexity     8658    10620    +1962     
============================================
  Files           500      709     +209     
  Lines         54930    69352   +14422     
  Branches       5867     7440    +1573     
============================================
+ Hits          27386    32681    +5295     
- Misses        24464    33002    +8538     
- Partials       3080     3669     +589     

Flag	Coverage Δ
unittests	47.12% <58.82%> (-2.74%)	⬇️

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

Impacted Files	Coverage Δ
...g/apache/pulsar/broker/lookup/TopicLookupBase.java	55.17% <ø> (+4.33%)	⬆️
...rg/apache/pulsar/broker/web/PulsarWebResource.java	58.34% <ø> (+2.68%)	⬆️
...va/org/apache/pulsar/broker/service/ServerCnx.java	48.34% <33.33%> (+0.53%)	⬆️
...pulsar/broker/admin/impl/PersistentTopicsBase.java	59.44% <72.72%> (+0.72%)	⬆️
...rvice/schema/KeyValueSchemaCompatibilityCheck.java	21.62% <0.00%> (-45.95%)	⬇️
...lsar/broker/loadbalance/impl/ThresholdShedder.java	3.27% <0.00%> (-27.05%)	⬇️
.../apache/pulsar/broker/loadbalance/LoadManager.java	61.11% <0.00%> (-16.67%)	⬇️
...tent/NonPersistentDispatcherMultipleConsumers.java	40.74% <0.00%> (-12.35%)	⬇️
...apache/pulsar/broker/service/TopicListService.java	40.80% <0.00%> (-12.00%)	⬇️
...pulsar/broker/service/PulsarCommandSenderImpl.java	66.32% <0.00%> (-9.19%)	⬇️
... and 250 more

[nicoloboschi]

Good catch!