[exporter/datadog] Always use http for logs agent exporter (#33504)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->

Add default config option to always use http for logs agent exporter.
Fixes bug where logs agent exporter was falling back to using tcp,
causing collector shut down.

Also opened a PR in datadog-agent for adding a warn log when the logs
agent connectivity check fails:
DataDog/datadog-agent#26626

**Link to tracking Issue:** <Issue number if applicable>
Fixes
#33195

**Testing:** <Describe what testing was performed and which tests were
added.>

**Documentation:** <Describe the documentation added.>

.chloggen/stanley.liu_logs-agent-use-http.yaml

@@ -0,0 +1,27 @@
+# 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: exporter/datadog
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Prevents collector shut down when Datadog logs pipeline fails to validate API key
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33195]
+
+# (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:
+
+# 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/datadogexporter/agent_components.go

@@ -35,6 +35,7 @@ func newConfigComponent(set component.TelemetrySettings, cfg *Config) coreconfig
 	pkgconfig.Set("logs_config.auditor_ttl", pkgconfigsetup.DefaultAuditorTTL, pkgconfigmodel.SourceDefault)
 	pkgconfig.Set("logs_config.batch_max_content_size", pkgconfigsetup.DefaultBatchMaxContentSize, pkgconfigmodel.SourceDefault)
 	pkgconfig.Set("logs_config.batch_max_size", pkgconfigsetup.DefaultBatchMaxSize, pkgconfigmodel.SourceDefault)
+	pkgconfig.Set("logs_config.force_use_http", true, pkgconfigmodel.SourceDefault)
 	pkgconfig.Set("logs_config.input_chan_size", pkgconfigsetup.DefaultInputChanSize, pkgconfigmodel.SourceDefault)
 	pkgconfig.Set("logs_config.max_message_size_bytes", pkgconfigsetup.DefaultMaxMessageSizeBytes, pkgconfigmodel.SourceDefault)
 	pkgconfig.Set("logs_config.run_path", "/opt/datadog-agent/run", pkgconfigmodel.SourceDefault)