add missing DEBUG_PORT env variable

[kadel]

What does this PR do?:

Debug commands are using DEBUG_PORT variable but that variable is not defined in containers.
This was not an issue for odo as it automatically injects this variable if it is not defined, but this creates problems for other tools.

Which issue(s) this PR fixes:

fixes one of the items in devfile/api#679

PR acceptance criteria:

• Contributing guide
  Have you read the devfile registry contributing guide and followed its instructions?
• Test automation
  Does this repository's tests pass with your changes?
• Documentation
  Does any documentation need to be updated with your changes?

[kadel]

java-quarkus is failing due to devfile/api#773

[elsony]

/retest

[elsony]

Does setting the debug port to the same port means we are increasing the chances of getting port conflict when running different types of applications at the same time? It is fairly common in tools, e.g. IDE, to have configurable debug port numbers, usually auto-generated. Do we need a debug port to explicitly set in every devfile?

[kadel]

Does setting the debug port to the same port means we are increasing the chances of getting port conflict when running different types of applications at the same time? It is fairly common in tools, e.g. IDE, to have configurable debug port numbers, usually auto-generated. Do we need a debug port to explicitly set in every devfile?

If we don't set it in the devfile then the tools will have to set it themself.
Currently, there is nothing in devfile spec that defines that tools should set this variable.
Odo sets it if it is not defined in the devfile, but Che doesn't so without setting it explicitly in devfile debug in Che won't work (devfile/api#777)

I don't think that this can create conflicts. Each devfile runs as a separate Deployment/Port/Container.

[elsony]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: elsony, kadel

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[johnmcollier]

/retest