chore(AI): paygTrialEvents flag cleanup (#10508)

This PR cleans up the paygTrialEvents flag. These changes were
automatically generated by AI and should be reviewed carefully.

Fixes #10506

## 🧹 AI Flag Cleanup Summary
The `paygTrialEvents` feature flag has been removed from the codebase.
Since no
conditional logic using this flag was found in this repository, only the
flag's
definition and configuration were removed.
⚠️ **Warning:** No conditional logic for this flag was found in the
provided
files. The logic may exist in another repository.
### 🚮 Removed
- **Configuration**
- Removed `paygTrialEvents` from the `IFlagKey` type in
`src/lib/types/experimental.ts`.
- Removed the `paygTrialEvents` flag definition from
`src/lib/types/experimental.ts`.
- Removed `paygTrialEvents` from the development server configuration in
`src/server-dev.ts`.
### 🛠 Kept
- **Feature**
- The `paygTrialEvents` feature is considered enabled by default now.
### 📝 Why
The feature flag `paygTrialEvents` was marked as completed with an
outcome of
"kept". The cleanup involves removing the flag and its related
definitions.

Co-authored-by: unleash-bot <194219037+unleash-bot[bot]@users.noreply.github.com>
Co-authored-by: Thomas Heartman <thomas@getunleash.io>

src/lib/types/experimental.ts

@@ -57,7 +57,6 @@ export type IFlagKey =
     | 'customMetrics'
     | 'impactMetrics'
     | 'changeRequestApproverEmails'
-    | 'paygTrialEvents'
     | 'paygInstanceStatsEvents'
     | 'lifecycleGraphs'
     | 'addConfiguration'
@@ -267,10 +266,6 @@ const flags: IFlags = {
         process.env.UNLEASH_EXPERIMENTAL_IMPACT_METRICS,
         false,
     ),
-    paygTrialEvents: parseEnvVarBoolean(
-        process.env.UNLEASH_EXPERIMENTAL_PAYG_TRIAL_EVENTS,
-        false,
-    ),
     paygInstanceStatsEvents: parseEnvVarBoolean(
         process.env.UNLEASH_EXPERIMENTAL_PAYG_INSTANCE_STATS_EVENTS,
         false,

src/server-dev.ts

@@ -54,7 +54,6 @@ process.nextTick(async () => {
                         reportUnknownFlags: true,
                         customMetrics: true,
                         impactMetrics: true,
-                        paygTrialEvents: true,
                         lifecycleGraphs: true,
                         addConfiguration: true,
                         projectListViewToggle: true,