Merge bitcoin/bitcoin#26408: test: Remove spam from debug log

ef97b89 Exclude rand from debug log (Jeff Ruane)

Pull request description:

  Currently, `debug.log` is spammed with messages like this from `random.cpp` when functional tests are run.

  ```
  2022-10-25T19:24:34.787663Z [scheduler] [random.cpp:519] [SeedPeriodic] [rand] Feeding 36565 bytes of dynamic environment data into RNG
  ```

  These logs are not useful for debugging and decrease the signal-to-noise ratio of the logs, so they should be suppressed by excluding the `rand` category, as the `libevent` and `leveldb` categories currently are.

ACKs for top commit:
  LarryRuane:
    ACK ef97b89
  kouloumos:
     ACK ef97b89, confirmed that this log level is only used in `random.cpp` and indeed it seems that it doesn't add any value to the debug.log during functional tests.
  satsie:
    ACK ef97b89
  theStack:
    ACK ef97b89

Tree-SHA512: 5cea384a3197f0ec77efa9efc77822914450ecf5546606568bbd432c3536040c772c57aef58d3bb083a2e5e756f690766fa1fb382ab1973748db238108a58746

Author: MacroFake

test/functional/test_framework/test_node.py

@@ -102,6 +102,7 @@ def __init__(self, i, datadir, *, chain, rpchost, timewait, timeout_factor, bitc
             "-debug",
             "-debugexclude=libevent",
             "-debugexclude=leveldb",
+            "-debugexclude=rand",
             "-uacomment=testnode%d" % i,
         ]
         if use_valgrind: