fix: make profiler configurable and disable it by default in non-debug mode

[martiis]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Tests pass?	maybe
Documented?	no
Fixed tickets	no
License	MIT

Summary
The profiler.yaml configuration was loaded unconditionally in OverblogGraphQLExtension::loadConfigFiles(), registering GraphQLCollector and ProfilerController in all environments — including production.

While the data_collector tag is harmless when the profiler is disabled (Symfony's ProfilerPass simply skips it), the kernel.event_listener tag on graphql.post_executor is processed by RegisterListenersPass independently.

This means GraphQLCollector::onPostExecutor() fired on every GraphQL request in production, performing:

• Parser::parse() — re-parsing the full GraphQL query into an AST
• $this->cloneVar($variables) — deep-cloning all query variables via Symfony's VarCloner
• $this->cloneVar($result) — deep-cloning the entire GraphQL response
• AST traversal of all operation definitions and fields

All this data was accumulated into $this->batches and never consumed, since collect() is only called by Symfony when the profiler is enabled.

Impact

• Eliminates unnecessary CPU overhead (query parsing + deep cloning) on every production GraphQL request
• Reduces memory usage from cloned result objects that were never read
• Removes an unused public controller endpoint (ProfilerController) from production