Update AVF backcompat tests to ignore bootargs/kernel-size

Ignore bootargs and investigate if bootargs can mutate the VM
Kernel size update

Bug: 391297376
Test: TH
Change-Id: Ic07db9c4ca405735e5142547da8244018f0c02ff
diff --git a/tests/backcompat_test/src/main.rs b/tests/backcompat_test/src/main.rs
index a7fb074..2bd1bec 100644
--- a/tests/backcompat_test/src/main.rs
+++ b/tests/backcompat_test/src/main.rs
@@ -151,6 +151,11 @@
         .arg("/chosen/kaslr-seed")
         .arg("--ignore-path-value")
         .arg("/chosen/rng-seed")
+        // TODO: b/391420337 Investigate if bootargs may mutate VM
+        .arg("--ignore-path-value")
+        .arg("/chosen/bootargs")
+        .arg("--ignore-path-value")
+        .arg("/config/kernel-size")
         .arg("--ignore-path-value")
         .arg("/avf/untrusted/instance-id")
         .arg("--ignore-path-value")