[DELTA-OSS-EXTERNAL] Allow Python vacuum(<integer>)

`vacuum(0)` was throwing the following error because the Java API has Double and Py4j was searching for integer. The fix is to convert the python parameter to float before calling java.

```
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/private/var/folders/0q/c_zjyddd4hn5j9jkv0jsjvl00000gp/T/spark-ff856d5c-6a62-45bd-b9a4-0a0fea0acd09/userFiles-de551310-4bed-4267-be1c-b3c36556d6ff/io.delta_delta-core_2.11-0.4.0.jar/delta/tables.py", line 210, in vacuum
  File "/usr/local/Cellar/spark/spark-2.4.3-bin-hadoop2.7/python/lib/py4j-0.10.7-src.zip/py4j/java_gateway.py", line 1257, in __call__
  File "/usr/local/Cellar/spark/spark-2.4.3-bin-hadoop2.7/python/pyspark/sql/utils.py", line 63, in deco
    return f(*a, **kw)
  File "/usr/local/Cellar/spark/spark-2.4.3-bin-hadoop2.7/python/lib/py4j-0.10.7-src.zip/py4j/protocol.py", line 332, in get_return_value
py4j.protocol.Py4JError: An error occurred while calling o49.vacuum. Trace:
py4j.Py4JException: Method vacuum([class java.lang.Integer]) does not exist
    at py4j.reflection.ReflectionEngine.getMethod(ReflectionEngine.java:318)
    at py4j.reflection.ReflectionEngine.getMethod(ReflectionEngine.java:326)
    at py4j.Gateway.invoke(Gateway.java:274)
    at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
    at py4j.commands.CallCommand.execute(CallCommand.java:79)
    at py4j.GatewayConnection.run(GatewayConnection.java:238)
    at java.lang.Thread.run(Thread.java:748)
```

Closes #198

Author: Tathagata Das <[email protected]>

#6557 is resolved by tdas/j0ag9ic6.

GitOrigin-RevId: 7a171b8c110d40d23b18bcfffc2c5b8e59d6c0f4

Author: tdas

python/delta/tables.py

@@ -207,7 +207,7 @@ def vacuum(self, retentionHours=None):
         if retentionHours is None:
             return DataFrame(jdt.vacuum(), self._spark._wrapped)
         else:
-            return DataFrame(jdt.vacuum(retentionHours), self._spark._wrapped)
+            return DataFrame(jdt.vacuum(float(retentionHours)), self._spark._wrapped)
 
     @since(0.4)
     def history(self, limit=None):

python/delta/tests/test_deltatable.py

@@ -289,6 +289,7 @@ def test_vacuum(self):
         self.__createFile('bac.txt', 'abcdf')
         self.assertEqual(True, self.__checkFileExists('abc.txt'))
         dt.vacuum()  # will not delete files as default retention is used.
+        dt.vacuum(1000)  # test whether integers work
 
         self.assertEqual(True, self.__checkFileExists('bac.txt'))
         retentionConf = "spark.databricks.delta.retentionDurationCheck.enabled"