[adaptive processor] Remove redundant function

[yurishkuro]

Which problem is this PR solving?

• The function was a duplicate of another public method

Description of the changes

• Remove the function and redirect callsites to invoke HandleRootSpan instead

How was this change tested?

• CI

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.80%. Comparing base (364832f) to head (0310c07).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5953      +/-   ##
==========================================
- Coverage   96.81%   96.80%   -0.01%     
==========================================
  Files         345      345              
  Lines       16528    16518      -10     
==========================================
- Hits        16001    15991      -10     
  Misses        340      340              
  Partials      187      187              

Flag	Coverage Δ
badger_v1	8.03% <ø> (ø)
badger_v2	1.82% <ø> (ø)
cassandra-3.x-v1	16.62% <ø> (ø)
cassandra-3.x-v2	1.75% <ø> (ø)
cassandra-4.x-v1	16.62% <ø> (ø)
cassandra-4.x-v2	1.75% <ø> (ø)
elasticsearch-6.x-v1	18.79% <ø> (ø)
elasticsearch-7.x-v1	18.85% <ø> (ø)
elasticsearch-8.x-v1	19.03% <ø> (ø)
elasticsearch-8.x-v2	1.82% <ø> (ø)
grpc_v1	9.49% <ø> (ø)
grpc_v2	7.16% <ø> (ø)
kafka-v1	9.74% <ø> (ø)
kafka-v2	1.82% <ø> (ø)
memory_v2	1.82% <ø> (+0.01%)	⬆️
opensearch-1.x-v1	18.90% <ø> (ø)
opensearch-2.x-v1	18.89% <ø> (ø)
opensearch-2.x-v2	1.81% <ø> (-0.02%)	⬇️
tailsampling-processor	0.46% <ø> (ø)
unittests	95.28% <100.00%> (-0.01%)	⬇️

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[mahadzaryab1]

lgtm!