Remove relative reference when it does not work

[pwalczysko]

Removing the variable insight_version in 4 places where it does not resolve.
Interestingly:

• the variable does resolve in local build of this repo
• the variable does not resolve when building the omero-guides repo (and make clean gives warns)
• the variable does not resolve on for example this page of the production guides
• the variable does resolve in some cases, for example https://omero-guides.readthedocs.io/projects/omero-guide-mde/en/latest/mde_customizeObjects.html?highlight=5.5.15#type-of-input-fields

This is also motivated by ome/omero-guides#56

cc @jburel @joshmoore

[jburel]

We should figure why it does not resolve.

[pwalczysko]

We should figure why it does not resolve.

No chance to debug this. See the description. I cannot repeat the problem locally in sufficient granularity. The variable either resolves locally on all occassions (when built from this repo) or it does not resolve on any occassion (when built from omero-guides). But on production omero-guides, it resolves on 2 cases out of 4 and it does not resolve in the other 2 cases. The warning must be where the production version is built, but I do not know where that is ?

[jburel]

is it a side effect of the mix of submodules (github) and subprojects (rtd)

[pwalczysko]

How to progress on this one ?

[jburel]

I did not have a chance to look at it.
Ideally I would like to avoid the suggested change