Fix #2529 normalized query for biological pathway

Removed unnecessary OPTIONAL block as labeling service sets
the ?pathwayDescription variable.

Styling change to the code: use the target variable.

scholia/app/templates/chemical_biological-processes.sparql

@@ -1,14 +1,14 @@
 PREFIX target: <http://www.wikidata.org/entity/{{ q }}>
 
-SELECT DISTINCT ?pathway ?pathwayLabel (CONCAT("/pathway/", SUBSTR(STR(?pathway), 32)) AS ?pathwayUrl) ?pathwayDescription WHERE {
-  VALUES ?chemical { target: }
-  ?chemical wdt:P361 ?pathway.
-  ?pathway wdt:P527 ?chemical.
-  ?pathway wdt:P31 wd:Q2996394.
-  OPTIONAL {
-      ?pathway schema:description ?pathwayDescription .
-      FILTER (LANG(?pathwayDescription) = "[AUTO_LANGUAGE],en")
-  }
+SELECT DISTINCT
+  ?pathway ?pathwayLabel
+  (CONCAT("/pathway/", SUBSTR(STR(?pathway), 32)) AS ?pathwayUrl)
+  ?pathwayDescription
+WHERE {
+  ?pathway wdt:P527 target: ;
+           wdt:P31 wd:Q2996394 .
+  target: wdt:P361 ?pathway .
   SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
-} ORDER BY ASC(?pathwayLabel)
-  LIMIT 250
+}
+ORDER BY ASC(?pathwayLabel)
+LIMIT 250