feat (flex_setup): flex_setup doesn't install casa on RHEL (DISA-STIG).

-------------------

### Description

Doesn't work installing of casa (using flex_setup.py) on RHEL (DISA-STIG).

Reproducing:

1. install Janssen on RHEL (DISA-STIG) platforms;
2. run
```
./flex/flex-linux-setup/flex_linux_setup/flex_setup.py --install-casa
```
3. output:
```
Backing up old Janssen setup directory
Downloading https://github.com/JanssenProject/jans/archive/refs/heads/main.zip as /tmp/tmpi8lofcim/main.zip
Extracting jans-setup package
Downloading https://github.com/sqlalchemy/sqlalchemy/archive/rel_1_3_23.zip to /tmp/tmpocxnqmb7/rel_1_3_23.zip
Download size: 3637021 bytes
Downloading https://files.pythonhosted.org/packages/20/8b/66600f5851ec7893ace9b74445d7eaf3499571b347e339d18c76c876b0f9/cryptography-37.0.4-cp36-abi3-manylinux_2_17_x86_64.manylinux2014_x86_64.whl to /tmp/tmpyefb0hsh/cryptography-37.0.4-cp36-abi3-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Download size: 4151466 bytes
Downloading https://github.com/jpadilla/pyjwt/archive/refs/tags/2.4.0.zip to /tmp/tmpps74vrdq/2.4.0.zip
Download size: 87283 bytes

Log Files:

/opt/jans/jans-setup/logs/flex-setup.log
/opt/jans/jans-setup/logs/flex-setup-error.log

/opt/jans/jans-setup/setup_app/pylib/jwt/utils.py:7: CryptographyDeprecationWarning: Python 3.6 is no longer supported by the Python core team. Therefore, support for it is deprecated in cryptography and will be removed in a future release.
from cryptography.hazmat.primitives.asymmetric.ec import EllipticCurve
Please wait while collecting properties...
Install Admin UI [Y/n]: n
Casa is allready installed on this system
Generate Gluu Passwurd API Keystore [Y/n]: y
Downloading Gluu Flex components
Extracting /opt/dist/jans/flex.zip
Enabling script A51E-76DA
Generating Gluu Passwurd API Keystore
Restarting Apache
Restarting Jans Auth
Restarting Janssen Config Api
Installation was completed.
```
4. after installing: **/opt/jans/jetty/casa** is created;
```
/opt/jans/jetty/casa/webapps
ls -l
-rw-------. 1 root root 442 Mar 29 06:43 casa.xml
```
I.e. file **casa.war** is not deployed.

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