[exporter/signalfx] Warn when dropping data points (#37484)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
Log dropped data points with over 36 dimensions at warn log level

.chloggen/warn_on_dropped_dp.yaml

@@ -0,0 +1,30 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: signalfxexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Warn on dropping metric data points when they have more than allowed dimension count
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [37484]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  The SignalFx exporter drops metric data points if they have more than 36 dimensions.
+  Currently, the exporter logs at debug level when this occurs.
+  With this change, the exporter will log at the warning level.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

exporter/signalfxexporter/internal/translation/converter.go

@@ -254,7 +254,7 @@ func (dpv *datapointValidator) isValidMetricName(name string) bool {
 
 func (dpv *datapointValidator) isValidNumberOfDimension(dp *sfxpb.DataPoint) bool {
 	if len(dp.Dimensions) > maxNumberOfDimensions {
-		dpv.logger.Debug("dropping datapoint",
+		dpv.logger.Warn("dropping datapoint",
 			zap.String("reason", invalidNumberOfDimensions),
 			zap.Stringer("datapoint", dp),
 			zap.Int("number_of_dimensions", len(dp.Dimensions)),