Remove Java flags from core

Setting these flags in `.bazelrc` incurred a required for a Java
toolchain. This, in turn, would require a dependency on
rules_nixpkgs_java from rules_nixpkgs_core to set up a Java toolchain.
I'd like to avoid that kind of circular dependency.

core/.bazelrc

@@ -1,22 +1,5 @@
 build --host_platform=@rules_nixpkgs_core//platforms:host
 
-# Using toolchain resolution can lead to spurious dependencies on
-# `@local_config_cc//:builtin_include_directory_paths`. This needs to be
-# resolved before `--incompatible_enable_cc_toolchain_resolution` can be
-# recommended for `nixpkgs_cc_configure_hermetic`.
-# build --incompatible_enable_cc_toolchain_resolution
-
-build --java_runtime_version=nixpkgs_java_11
-build --java_language_version=11
-build --tool_java_runtime_version=nixpkgs_java_11
-build --tool_java_language_version=11
-
-# The following lines provide a workaround for a test failure in on the Java
-# toolchain on MacOS 11, documented here: https://github.com/tweag/rules_nixpkgs/issues/299.
-# They should be removed as soon as that issue has been resolved.
-build --enable_platform_specific_config
-build:macos --experimental_strict_java_deps=warn
-
 # User Configuration
 # ------------------
 try-import %workspace%/.bazelrc.local

toolchains/java/.bazelrc

@@ -0,0 +1,22 @@
+build --host_platform=@rules_nixpkgs_core//platforms:host
+
+# Using toolchain resolution can lead to spurious dependencies on
+# `@local_config_cc//:builtin_include_directory_paths`. This needs to be
+# resolved before `--incompatible_enable_cc_toolchain_resolution` can be
+# recommended for `nixpkgs_cc_configure_hermetic`.
+# build --incompatible_enable_cc_toolchain_resolution
+
+build --java_runtime_version=nixpkgs_java_11
+build --java_language_version=11
+build --tool_java_runtime_version=nixpkgs_java_11
+build --tool_java_language_version=11
+
+# The following lines provide a workaround for a test failure in on the Java
+# toolchain on MacOS 11, documented here: https://github.com/tweag/rules_nixpkgs/issues/299.
+# They should be removed as soon as that issue has been resolved.
+build --enable_platform_specific_config
+build:macos --experimental_strict_java_deps=warn
+
+# User Configuration
+# ------------------
+try-import %workspace%/.bazelrc.local