RFR: 8299213: Bad cast in GrowableArrayWithAllocator<>::grow

[Afshin Zafari]

### Description 
The grow size was wrongfully casted from `int` to `uint32`.

### Patch
The casting is removed.

### Tests
Local: **gtest:GrowableArrays***
mach5 tier1-5

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Commit messages:
 - 8299213: Bad cast in GrowableArrayWithAllocator<>::grow

Changes: https://git.openjdk.org/jdk/pull/12007/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12007&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299213
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12007.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12007/head:pull/12007

PR: https://git.openjdk.org/jdk/pull/12007