update serverless tidb_gc_life_time restriction (pingcap#19511) (ping…

…cap#19513)

system-variables.md

@@ -2955,16 +2955,12 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
 
 ### tidb_gc_life_time <span class="version-mark">New in v5.0</span>
 
-> **Note:**
->
-> This variable is read-only for [TiDB Cloud Serverless](https://docs.pingcap.com/tidbcloud/select-cluster-tier#tidb-cloud-serverless).
-
 - Scope: GLOBAL
 - Persists to cluster: Yes
 - Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
 - Type: Duration
 - Default value: `10m0s`
-- Range: `[10m0s, 8760h0m0s]`
+- Range: `[10m0s, 8760h0m0s]` for TiDB Self-Managed and [TiDB Cloud Dedicated](https://docs.pingcap.com/tidbcloud/select-cluster-tier#tidb-cloud-dedicated), `[10m0s, 168h0m0s]` for [TiDB Cloud Serverless](https://docs.pingcap.com/tidbcloud/select-cluster-tier#tidb-cloud-serverless)
 - The time limit during which data is retained for each GC, in the format of Go Duration. When a GC happens, the current time minus this value is the safe point.
 
 > **Note:**

tidb-cloud/limited-sql-features.md

@@ -160,7 +160,6 @@ TiDB Cloud works with almost all workloads that TiDB supports, but there are som
 | `tidb_force_priority` | Not supported [^4] | Not supported [^4] |
 | `tidb_gc_concurrency` | No limitation | Read-only [^10] |
 | `tidb_gc_enable` | No limitation | Read-only [^10] |
-| `tidb_gc_life_time` | No limitation | Read-only [^10] |
 | `tidb_gc_max_wait_time` | No limitation | Read-only [^10] |
 | `tidb_gc_run_interval` | No limitation | Read-only [^10] |
 | `tidb_gc_scan_lock_mode` | No limitation | Read-only [^10] |