[util] fix TidyBot warnings in ScopedTracer

This patch removes superfluous constructs from ScopedTracer, addressing
warnings output by CLANG tidy, e.g.:

  2024-04-24 18:49:17,524 INFO: src/kudu/util/debug/trace_event.h:1379:3: warning: 5 uninitialized fields at the end of the constructor call [
  clang-analyzer-optin.cplusplus.UninitializedObject]
    ScopedTracer() : p_data_(nullptr) {}
    ^
  ...

This patch doesn't contain any functional modifications.

Change-Id: I0e2f8578180955d0c8c788a0ee160deefba6a3ca
Reviewed-on: http://gerrit.cloudera.org:8080/21352
Reviewed-by: Mahesh Reddy <mreddy@cloudera.com>
Reviewed-by: Yingchun Lai <laiyingchun@apache.org>
Tested-by: Alexey Serbin <alexey@apache.org>
1 file changed