[mongodbatlasreceiver] Use default http transport that looks at proxy…

… environment variables (#36513)

.chloggen/mongodbatlas-default-transport.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: mongodbatlasreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Update the mongoDB Atlas receiver to use the Default HTTP Transport that supports default proxy configuration
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [36412]
+
+# (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: [user]

receiver/mongodbatlasreceiver/internal/mongodb_atlas_client.go

@@ -135,7 +135,7 @@ func NewMongoDBAtlasClient(
 	backoffConfig configretry.BackOffConfig,
 	log *zap.Logger,
 ) *MongoDBAtlasClient {
-	defaultTransporter := &http.Transport{}
+	defaultTransporter := http.DefaultTransport.(*http.Transport)
 	t := digest.NewTransportWithHTTPTransport(publicKey, privateKey, defaultTransporter)
 	roundTripper := newClientRoundTripper(t, log, backoffConfig)
 	tc := &http.Client{Transport: roundTripper}