bdd tests: get rid of dependency on build path

BDD tests will now use whatever osm2pgsql they find in the PATH.
For testing against legacy tokenizer, use -DSERVER_MODULE_PATH
to point to the module. This will no longer work out of the box.

docs/develop/Development-Environment.md

@@ -50,6 +50,10 @@ The documentation is built with mkdocs:
 * [mkdocstrings](https://mkdocstrings.github.io/) >= 0.25
 * [mkdocs-material](https://squidfunk.github.io/mkdocs-material/)
 
+Please be aware that tests always run against the globally installed
+osm2pgsql, so you need to have this set up. If you want to test against
+the vendored version of osm2pgsql, you need to set the PATH accordingly.
+
 ### Installing prerequisites on Ubuntu/Debian
 
 The Python tools should always be run with the most recent version.

docs/develop/Testing.md

@@ -78,7 +78,6 @@ To run the functional tests, do
 
 The tests can be configured with a set of environment variables (`behave -D key=val`):
 
- * `BUILDDIR` - build directory of Nominatim installation to test
  * `TEMPLATE_DB` - name of template database used as a skeleton for
                    the test databases (db tests)
  * `TEST_DB` - name of test database (db tests)
@@ -91,7 +90,7 @@ The tests can be configured with a set of environment variables (`behave -D key=
  * `DB_USER` - (optional) username of database login
  * `DB_PASS` - (optional) password for database login
  * `SERVER_MODULE_PATH` - (optional) path on the Postgres server to Nominatim
-                          module shared library file
+                          module shared library file (only needed for legacy tokenizer)
  * `REMOVE_TEMPLATE` - if true, the template and API database will not be reused
                        during the next run. Reusing the base templates speeds
                        up tests considerably but might lead to outdated errors