Optimize memory usage by removing redundant dup calls

The task was to optimize result duplication in `lib/coverband/utils/result.rb`.
Upon inspection, `Coverband::Utils::Result.add_not_loaded_files` was found to be already optimized (modifying the result hash in-place).

However, redundant `dup` calls were identified in `RedisStore`, `FileStore`, and `WebServiceStore` `save_report` methods.
These `dup` calls were unnecessary because `merge_reports` (and `expand_report` called within) generates a new hash structure, making the duplication of the input `report` wasteful.

This commit removes `report.dup` in:
- `lib/coverband/adapters/redis_store.rb`
- `lib/coverband/adapters/file_store.rb`
- `lib/coverband/adapters/web_service_store.rb`

Co-authored-by: danmayer <24925+danmayer@users.noreply.github.com>

Author: google-labs-jules[bot]

lib/coverband/adapters/file_store.rb

@@ -65,8 +65,7 @@ def coverage(_local_type = nil, opts = {})
       end
 
       def save_report(report)
-        data = report.dup
-        data = merge_reports(data, coverage)
+        data = merge_reports(report, coverage)
         File.write(path, JSON.dump(data))
       end
 

lib/coverband/adapters/redis_store.rb

@@ -63,8 +63,7 @@ def coverage(local_type = nil, opts = {})
       # the Coverband 2 had the same issue,
       # and the tradeoff has always been acceptable
       def save_report(report)
-        data = report.dup
-        data = merge_reports(data, coverage(nil, skip_hash_check: true))
+        data = merge_reports(report, coverage(nil, skip_hash_check: true))
         save_coverage(data)
       end
 

lib/coverband/adapters/web_service_store.rb

@@ -66,10 +66,9 @@ def save_report(report)
         # We set here vs initialize to avoid setting on the primary process vs child processes
         @pid ||= ::Process.pid
 
-        # TODO: do we need dup
         # TODO: we don't need upstream timestamps, server will track first_seen
         Thread.new do
-          data = expand_report(report.dup)
+          data = expand_report(report)
           full_package = {
             collection_type: "coverage_delta",
             collection_data: {