Remove beta notices for searchcache docs (#3823)

These noticed have been there since 2019:

#1445
#1463
#1471
#1498

They've been stable since then, so not beta.

api/query/README.md

@@ -40,8 +40,6 @@ Combines the filters such that there exists some result in the row that satisfie
 
 #### All and None
 
-> BETA: This feature is under development and may change without warning.
-
     all([query1] [query2])
 
 Combines filters such that they must all apply to all runs.
@@ -61,8 +59,6 @@ useful when there are multiple runs with the same product, e.g. to find a regres
 
 #### Count
 
-> BETA: This feature is under development and may change without warning.
-
     count:[number]([query1] [query2])
 
 Requires that the number of results matching the given query/queries is precisely
@@ -79,8 +75,6 @@ Safari is the only one missing a result:
 
 ##### Count inequality
 
-> BETA: This feature is under development and may change without warning.
-
     count[inequality][number]([query1])
 
 Requires that the number of results matching the given query satisfies the given
@@ -151,8 +145,6 @@ Where `[product]` is a product specification (e.g. `safari`, `chrome-69`).
 
 #### Meta qualities
 
-> BETA: This feature is under development and may change without warning.
-
 Filters the results to values which possess/exhibit a given quality.
 
     is:[quality]