ART benchmarks: use 18.04 image

The bash version in 16.04 is no longer supported by the main script.

Change-Id: I56e49f3f81368b822809ac7456594e3e87afa73f
diff --git a/android/nexus5x/microbenchmarks_32.yaml b/android/nexus5x/microbenchmarks_32.yaml
index 81ffe0f..286ab1a 100644
--- a/android/nexus5x/microbenchmarks_32.yaml
+++ b/android/nexus5x/microbenchmarks_32.yaml
@@ -23,7 +23,7 @@
    lava-lxc:
      name: lxc-microbenchmarks
      distribution: ubuntu
-     release: xenial
+     release: bionic
      arch: amd64
      verbose: true
 
diff --git a/android/nexus5x/microbenchmarks_64.yaml b/android/nexus5x/microbenchmarks_64.yaml
index 1bc031d..8ed7248 100644
--- a/android/nexus5x/microbenchmarks_64.yaml
+++ b/android/nexus5x/microbenchmarks_64.yaml
@@ -23,7 +23,7 @@
    lava-lxc:
      name: lxc-microbenchmarks
      distribution: ubuntu
-     release: xenial
+     release: bionic
      arch: amd64
      verbose: true
 
diff --git a/android/pixel2/microbenchmarks_32.yaml b/android/pixel2/microbenchmarks_32.yaml
index ec5acdf..e61e26a 100644
--- a/android/pixel2/microbenchmarks_32.yaml
+++ b/android/pixel2/microbenchmarks_32.yaml
@@ -23,7 +23,7 @@
    lava-lxc:
      name: lxc-microbenchmarks
      distribution: ubuntu
-     release: xenial
+     release: bionic
      arch: amd64
      verbose: true
 
diff --git a/android/pixel2/microbenchmarks_64.yaml b/android/pixel2/microbenchmarks_64.yaml
index dc389fd..3aba922 100644
--- a/android/pixel2/microbenchmarks_64.yaml
+++ b/android/pixel2/microbenchmarks_64.yaml
@@ -23,7 +23,7 @@
    lava-lxc:
      name: lxc-microbenchmarks
      distribution: ubuntu
-     release: xenial
+     release: bionic
      arch: amd64
      verbose: true
 
diff --git a/android/pixel3/microbenchmarks_32.yaml b/android/pixel3/microbenchmarks_32.yaml
index 87252fa..1dd346f 100644
--- a/android/pixel3/microbenchmarks_32.yaml
+++ b/android/pixel3/microbenchmarks_32.yaml
@@ -23,7 +23,7 @@
    lava-lxc:
      name: lxc-microbenchmarks
      distribution: ubuntu
-     release: xenial
+     release: bionic
      arch: amd64
      verbose: true
 
diff --git a/android/pixel3/microbenchmarks_64.yaml b/android/pixel3/microbenchmarks_64.yaml
index 183987e..5817755 100644
--- a/android/pixel3/microbenchmarks_64.yaml
+++ b/android/pixel3/microbenchmarks_64.yaml
@@ -23,7 +23,7 @@
    lava-lxc:
      name: lxc-microbenchmarks
      distribution: ubuntu
-     release: xenial
+     release: bionic
      arch: amd64
      verbose: true