Stop calling 'env default -a'

That command is no longer needed because the u-boot environment is now
partially stored directly in the image. Everytime the image is reflashed, the
environment is wiped out.

Signed-off-by: Frédéric Dalleau <frederic.dalleau@collabora.com>

test-cases/apertis-update-manager-api.yaml

@@ -16,7 +16,6 @@ metadata:
     - "A static update bundle file of the same architecture, variant and version as the testing image"
     - "A Fat32 USB flash drive, preloaded with the update bundle at the root of the disk"
     - "Downloaded update file (with '.delta' extension) should be copied to flash drive using the name 'static-update.bundle'"
-    - "The DUT u-boot environment must be clean: in u-boot, run: `env default -a` followed by `saveenv`"
     - "A PC must be connected to DUT serial port"
 
   expected:

test-cases/apertis-update-manager-automount.yaml

@@ -15,7 +15,6 @@ metadata:
     - "A static update bundle file of the same architecture, variant and version as the testing image"
     - "A Fat32 USB flash drive, preloaded with the update bundle at the root of the disk"
     - "Downloaded update file (with '.delta' extension) should be copied to flash drive using the name 'static-update.bundle'"
-    - "The DUT u-boot environment must be clean: in u-boot, run: `env default -a` followed by `saveenv`"
     - "A PC must be connected to DUT serial port"
 
   expected:

test-cases/apertis-update-manager-diskfull.yaml

@@ -16,7 +16,6 @@ metadata:
     - "A static update bundle file of the same architecture, variant and version as the testing image"
     - "A Fat32 USB flash drive, preloaded with the update bundle at the root of the disk"
     - "Downloaded update file (with '.delta' extension) should be copied to flash drive using the name 'static-update.bundle'"
-    - "The DUT u-boot environment must be clean: in u-boot, run: `env default -a` followed by `saveenv`"
     - "A PC must be connected to DUT serial port"
 
   expected:

test-cases/apertis-update-manager-powercut.yaml

@@ -16,7 +16,6 @@ metadata:
     - "A static update bundle file of the same architecture, variant and version as the testing image"
     - "A Fat32 USB flash drive, preloaded with the update bundle at the root of the disk"
     - "Downloaded update file (with '.delta' extension) should be copied to flash drive using the name 'static-update.bundle'"
-    - "The DUT u-boot environment must be clean: in u-boot, run: `env default -a` followed by `saveenv`"
     - "A PC must be connected to DUT serial port"
 
   expected:

test-cases/apertis-update-manager-rollback.yaml

@@ -16,7 +16,6 @@ metadata:
     - "A static update bundle file of the same architecture, variant and version as the testing image"
     - "A Fat32 USB flash drive, preloaded with the update bundle at the root of the disk"
     - "Downloaded update file (with '.delta' extension) should be copied to flash drive using the name 'static-update.bundle'"
-    - "The DUT u-boot environment must be clean: in u-boot, run: `env default -a` followed by `saveenv`"
     - "A PC must be connected to DUT serial port"
 
   expected:

test-cases/apertis-update-manager-usb-unplug.yaml

@@ -15,7 +15,6 @@ metadata:
     - "A static update bundle file of the same architecture, variant and version as the testing image"
     - "A Fat32 USB flash drive, preloaded with the update bundle at the root of the disk"
     - "Downloaded update file (with '.delta' extension) should be copied to flash drive using the name 'static-update.bundle'"
-    - "The DUT u-boot environment must be clean: in u-boot, run: `env default -a` followed by `saveenv`"
     - "A PC must be connected to DUT serial port"
 
   expected: