update_kernel_afdo: Remove 3.18

Remove 3.18 from the kernel AFDO update.

BUG=b:199787442
TEST=./update_kernel_afdo

Change-Id: I343d2048fb6bbd9c3c9f37bdfe64526a91c68220
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3162669
Tested-by: Denis Nikitin <denik@chromium.org>
Reviewed-by: Bob Haarman <inglorion@chromium.org>
Commit-Queue: Denis Nikitin <denik@chromium.org>
diff --git a/afdo_tools/update_kernel_afdo b/afdo_tools/update_kernel_afdo
index 4b41053..f539ee9 100755
--- a/afdo_tools/update_kernel_afdo
+++ b/afdo_tools/update_kernel_afdo
@@ -25,7 +25,7 @@
 set -o pipefail
 
 GS_BASE=gs://chromeos-prebuilt/afdo-job/vetted/kernel
-KVERS="3.18 4.4 4.14 4.19 5.4"
+KVERS="4.4 4.14 4.19 5.4"
 failed_channels=""
 
 script_dir=$(dirname "$0")
@@ -180,7 +180,6 @@
     canary )
       commit_contents="afdo_metadata: Publish the new kernel profiles
 
-Update chromeos-kernel-3_18
 Update chromeos-kernel-4_4
 Update chromeos-kernel-4_14
 Update chromeos-kernel-4_19