Use clang-19 for rebalancer OSS Linux builds

Summary:
- Create clang19 manifest with debs for Ubuntu 24.04
- Add clang19 as a Linux dependency for rebalancer, replacing gcc14 (which
  only has packages for CentOS Stream 9) in the general dependencies
- Set CMAKE_C_COMPILER=clang-19 and CMAKE_CXX_COMPILER=clang++-19 for Linux

Reviewed By: sahilsd

Differential Revision: D96800042

fbshipit-source-id: b27714100e45ab6a5cfadc5e949051035ab635e5

Author: r-barnes

build/fbcode_builder/manifests/clang19

@@ -0,0 +1,8 @@
+[manifest]
+name = clang19
+
+[debs.os=linux]
+clang-19
+
+[rpms.os=linux]
+clang

build/fbcode_builder/manifests/rebalancer

@@ -20,12 +20,18 @@ fbthrift
 fizz
 fmt
 folly
-gcc14
 gflags
 glog
 googletest
 xxhash
 
+[dependencies.os=linux]
+clang19
+
+[cmake.defines.os=linux]
+CMAKE_C_COMPILER=clang-19
+CMAKE_CXX_COMPILER=clang++-19
+
 [cmake.defines.os=darwin]
 REBALANCER_USE_SCIP=0
 
@@ -38,8 +44,8 @@ fbcode/algopt/rebalancer = algopt/rebalancer
 fbcode/algopt/lp = algopt/lp
 
 [dependencies.all(distro=centos_stream,distro_vers=9)]
-gcc14
+clang19
 
 [cmake.defines.all(distro=centos_stream,distro_vers=9)]
-CMAKE_C_COMPILER=/opt/rh/gcc-toolset-14/root/usr/bin/gcc
-CMAKE_CXX_COMPILER=/opt/rh/gcc-toolset-14/root/usr/bin/g++
+CMAKE_C_COMPILER=clang-19
+CMAKE_CXX_COMPILER=clang++-19