Allow passing of install task variables to downstream tasks of a dag

[Harshith-umesh]

Description

This fix makes it possible to pass variables generated in the install task namely the cluster name and UUID of the install task for rosa and rogcp dags. The passed variables can be accessed by any of the following tasks(benchmarks,cleanup etc) in the dag.
A limitation of the bash operator is that only a single string can be passed from a task(script), so a concatenation of the above 2 vars, separated by '@' delimiter is passed, the receiving tasks have to separate the 2 from the pulled string.
Dag run eg: dag link
The passed string is accessible to the benchmark scripts and the cleanup script.

Fixes

https://issues.redhat.com/browse/PERFSCALE-1520

[morenod]

LGTM

[codecov-commenter]

Codecov Report

Merging #218 (c9449c3) into master (1b34f37) will decrease coverage by 0.07%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master     #218      +/-   ##
==========================================
- Coverage   93.32%   93.24%   -0.08%     
==========================================
  Files          24       24              
  Lines        1003     1007       +4     
==========================================
+ Hits          936      939       +3     
- Misses         67       68       +1     

Flag	Coverage Δ
gha	93.24% <75.00%> (-0.08%)	⬇️
python-3.9	93.24% <75.00%> (-0.08%)	⬇️
unit	93.24% <75.00%> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...penshift_nightlies/tasks/utils/final_dag_status.py	47.05% <0.00%> (-2.95%)	⬇️
dags/openshift_nightlies/tasks/benchmarks/e2e.py	92.75% <100.00%> (ø)
...s/openshift_nightlies/tasks/install/rogcp/rogcp.py	100.00% <100.00%> (ø)
...ags/openshift_nightlies/tasks/install/rosa/rosa.py	100.00% <100.00%> (ø)
...t_nightlies/tasks/install/hypershift/hypershift.py	100.00% <0.00%> (ø)
dags/openshift_nightlies/models/release.py	97.67% <0.00%> (+0.05%)	⬆️

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