Enclose input_gate_lock_hold and input_gate_lock_wait spans into inpu…

[shrima-cf]

…t_gate_wait_attempt parent span

This will help group the lock and wait span from a single request together

I noticed from this span - https://tracing.cfdata.org/trace/000f2d35a668d2bb that the lock_wait and lock_holds are grouped individually, making it hard to tie the hold and wait to a single request. This change will help fix the issue.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.15%. Comparing base (d6fce98) to head (d9f80b3).

Files with missing lines	Patch %	Lines
src/workerd/io/io-gate.c++	77.77%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5948   +/-   ##
=======================================
  Coverage   70.14%   70.15%           
=======================================
  Files         407      407           
  Lines      107306   107307    +1     
  Branches    17985    17985           
=======================================
+ Hits        75273    75281    +8     
+ Misses      21242    21232   -10     
- Partials    10791    10794    +3     

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