storage: deprecate bogus timestamp adjusting codepaths

This stuff is all deprecated since we have timestamp validation in
the produce path, and is actually quite undesirable behavior now.

The cluster property `storage_ignore_timestamps_in_future_sec` should
be eventually deprecated after enough time has passed (at the same time,
we should set the `available_policy` of `validated_batch_timestamps`
from `new_clusters_only` to `always`).

Author: WillemKauf

src/v/storage/disk_log_impl.cc

@@ -398,30 +398,40 @@ disk_log_impl::time_based_gc_max_offset(gc_config cfg) const {
                     : _segs.front()->index().retention_timestamp(retention_cfg),
       retention_cfg);
 
+    auto validated_timestamps = _feature_table.local().is_active(
+      features::feature::validated_batch_timestamps);
     static constexpr auto const_threshold = 1min;
     auto bogus_threshold = model::timestamp(
       model::timestamp::now().value() + const_threshold / 1ms);
 
     auto it = std::find_if(
       std::cbegin(_segs),
       std::cend(_segs),
-      [this, time = cfg.eviction_time, bogus_threshold, retention_cfg](
-        const ss::lw_shared_ptr<segment>& s) {
+      [this,
+       time = cfg.eviction_time,
+       bogus_threshold,
+       retention_cfg,
+       validated_timestamps](const ss::lw_shared_ptr<segment>& s) {
           auto retention_ts = s->index().retention_timestamp(retention_cfg);
 
-          if (retention_ts > bogus_threshold) {
-              // Warn on timestamps more than the "bogus" threshold in future
-              // this should not fire for segments created after v23.3
-              vlog(
-                gclog.warn,
-                "[{}] found segment with bogus retention timestamp: {} (base "
-                "{}, max {}) - {}",
-                config().ntp(),
-                retention_ts,
-                s->index().base_timestamp(),
-                s->index().max_timestamp(),
-                s->index().broker_timestamp(),
-                s);
+          if (!validated_timestamps) {
+              // Deprecated code path for >= v25.3.1.
+              if (retention_ts > bogus_threshold) {
+                  // Warn on timestamps more than the "bogus" threshold in
+                  // future this should not fire for segments created after
+                  // v23.3
+                  vlog(
+                    gclog.warn,
+                    "[{}] found segment with bogus retention timestamp: {} "
+                    "(base "
+                    "{}, max {}) - {}",
+                    config().ntp(),
+                    retention_ts,
+                    s->index().base_timestamp(),
+                    s->index().max_timestamp(),
+                    s->index().broker_timestamp(),
+                    s);
+              }
           }
 
           // first that is not going to be collected
@@ -1776,6 +1786,12 @@ ss::future<std::optional<model::offset>> disk_log_impl::do_gc(gc_config cfg) {
 }
 
 ss::future<> disk_log_impl::maybe_adjust_retention_timestamps() {
+    auto validated_timestamps = _feature_table.local().is_active(
+      features::feature::validated_batch_timestamps);
+    if (validated_timestamps) {
+        // Deprecated code path for >= v25.3.1.
+        co_return;
+    }
     // Correct any timestamps too far in the future, meant to be called before
     // calculating the retention offset for garbage collection.
     // It's expected that this will be used only for segments pre v23.3,