Remove blocking CollectNow commands to fix heartbeat stability

Eliminates automatic CollectNow command sending on host connection which
was blocking the main message processing loop for up to 5 seconds per
command. Since agents transmit cached data every 2 seconds anyway, the
CollectNow optimization provided minimal benefit while causing heartbeat
detection issues. Also removes unused send_command wrapper method.

This should completely resolve intermittent host connection dropping.

Cargo.lock

@@ -270,7 +270,7 @@ checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
 
 [[package]]
 name = "cm-dashboard"
-version = "0.1.69"
+version = "0.1.72"
 dependencies = [
  "anyhow",
  "chrono",
@@ -292,7 +292,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-agent"
-version = "0.1.69"
+version = "0.1.72"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -315,7 +315,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-shared"
-version = "0.1.69"
+version = "0.1.72"
 dependencies = [
  "chrono",
  "serde",