Unable to create network after enabling the trunk service plug-in

Brief Description
-----------------
Unable to create network after enabling the trunk service plug-in

Severity
--------
Minor

Steps to Reproduce
------------------
Create yaml file containing:
conf:
 neutron:
   DEFAULT:
     service_plugins:
     - trunk

$ system helm-override-update --values <yaml_file> stx-openstack neutron openstack
$ system application-apply stx-openstack
wait for apply to finish
$ openstack network create test_net

Expected Behavior
------------------
network successfully created

Actual Behavior
----------------
Error while executing command: HttpException: 503, Unable to create the network. No tenant network is available for allocation.

Reproducibility
---------------
always

Branch/Pull Time/Commit
-----------------------
###
### StarlingX
### Built from master
###

OS="centos"
SW_VERSION="20.12"
BUILD_TARGET="Host Installer"
BUILD_TYPE="Formal"
BUILD_ID="20210317T013430Z"

JOB="STX_build_layer_flock_master_master"
<email address hidden>"
BUILD_NUMBER="426"
BUILD_HOST="starlingx_mirror"
BUILD_DATE="2021-03-17 01:34:30 +0000"

FLOCK_OS="centos"
FLOCK_JOB="STX_build_layer_flock_master_master"
<email address hidden>"
FLOCK_BUILD_NUMBER="426"
FLOCK_BUILD_HOST="starlingx_mirror"
FLOCK_BUILD_DATE="2021-03-17 01:34:30 +0000"

DISTRO_OS="centos"
DISTRO_JOB="STX_build_layer_distro_master_master"
<email address hidden>"
DISTRO_BUILD_NUMBER="432"
DISTRO_BUILD_HOST="starlingx_mirror"
DISTRO_BUILD_DATE="2021-03-14 07:14:02 +0000"

COMPILER_OS="centos"
COMPILER_JOB="STX_build_layer_compiler_master_master"
<email address hidden>"
COMPILER_BUILD_NUMBER="487"
COMPILER_BUILD_HOST="starlingx_mirror"
COMPILER_BUILD_DATE="2021-03-12 18:13:44 +0000"

Test Activity
-------------
Regression Testing

Workaround
----------
If the network is created before "helm-override-update", "opentasck network trunk create" is successful