What I did was creating an additional yaml file containing all this global config which is used in all bundles.
f.e. in a folder /common or /global you can define a 'globalconf.yml'.
In this file you define your global variables (in the variables section, like in databricks.yml), and you can even define your targets here (except for workspace URL, that is not permitted last time I checked).

Now, this file you include into your databricks.yml using the include section:

databricks.yml is now able to read the content of globalconf.yml.
We still have to pass this to the resources dir (job definition).  This can be done by defining variables in the databricks yaml which are filled with values of globalconf yaml.
(the files that reside in /resources cannot access the globalconf yaml file, only databricks yaml).
Like this you can put a ton of config into a global file.
Not sure if it makes sense.