feat(redis): add DD_TRACE_REDIS_LIFECYCLE_COMMANDS_ENABLED to disable lifecycle spans

[jbdelhommeau]

Summary

Add DD_TRACE_REDIS_LIFECYCLE_COMMANDS_ENABLED (boolean, default true) to allow users to disable tracing of Redis lifecycle/admin/introspection operations independently from data commands.

Motivation

Applications using Redis heavily generate many low-value spans (connect, close, auth, ping, getHost, isConnected, bgSave, etc.) that add noise without observability value. Users want to reduce span volume without disabling the entire Redis integration.

Proposed behaviour

When DD_TRACE_REDIS_LIFECYCLE_COMMANDS_ENABLED=false:

• PHPRedis: 27 lifecycle methods NOT traced: connect, pconnect, open, popen, close, auth, select, ping, echo, isConnected, getHost, getPort, getDbNum, getTimeout, getReadTimeout, bgRewriteAOF, bgSave, flushAll, flushDb, save, restore, swapdb, _serialize, _unserialize, getLastError, clearLastError, RedisCluster.__construct
• Predis: 3 methods NOT traced: __construct, connect, executePipeline
• Connection metadata (ObjectKVStore) is preserved so data command spans still have out.host tags
• All 120+ data commands (get, set, hGet, etc.), multi, exec remain traced

Prior art

Same pattern as DD_TRACE_PDO_PREPARED_STATEMENTS_ENABLED (PR #3752) and Go tracer's WithIgnoreQueryTypes.

Implementation scope

• ext/configuration.h — declare CONFIG(BOOL, DD_TRACE_REDIS_LIFECYCLE_COMMANDS_ENABLED, "true")
• src/DDTrace/Integrations/PHPRedis/PHPRedisIntegration.php — conditional hook registration
• src/DDTrace/Integrations/Predis/PredisIntegration.php — conditional hook registration
• metadata/supported-configurations.json — document the variable
• Tests for both integrations