[8.12](backport #40508) [aws] Update max_number_of_messages doc (#40513)

* Update max_number_of_messages doc (#40508)

(cherry picked from commit 0567022)

# Conflicts:
#	x-pack/filebeat/docs/inputs/input-aws-s3.asciidoc

* Update input-aws-s3.asciidoc

* fix ci

---------

Co-authored-by: kaiyan-sheng <[email protected]>

.buildkite/pipeline.py

@@ -143,8 +143,8 @@ def __init__(self):
         self.files: list[str] = []
 
     def get_pr_changeset(self) -> list[str]:
-        base_branch = os.getenv("BUILDKITE_PULL_REQUEST_BASE_BRANCH", "main")
-        diff_command = ["git", "diff", "--name-only", "{}...HEAD".format(base_branch)]
+        hash = ["git", "rev-parse", "8.12"]
+        diff_command = ["git", "diff", "--name-only", "{}...HEAD".format(hash)]
         result = subprocess.run(diff_command, stdout=subprocess.PIPE)
         if result.returncode == 0:
             self.files = result.stdout.decode().splitlines()

x-pack/filebeat/docs/inputs/input-aws-s3.asciidoc

@@ -261,7 +261,13 @@ The default is `10 MiB`.
 ==== `max_number_of_messages`
 
 The maximum number of SQS messages that can be inflight at any time. Defaults
-to 5.
+to 5. Setting this parameter too high can overload Elastic Agent and cause
+ingest failures in situations where the SQS messages contain many S3 objects
+or the S3 objects themselves contain large numbers of messages.
+We recommend to keep the default value 5 and use the `Balanced` or `Optimized for
+Throughput` setting in the
+{fleet-guide}/es-output-settings.html#es-output-settings-performance-tuning-settings[preset]
+options to tune your Elastic Agent performance.
 
 [id="input-{type}-parsers"]
 [float]