ci: Use documented `CCACHE_MAXSIZE` instead of `CCACHE_SIZE`

This change aims to:
1) Remove our own `CCACHE_SIZE` environment variable that violates
Ccache's `CCACHE_*` namespace.
2) Introduce the `CCACHE_MAXSIZE` environment variable that is
documented since v3.3, which makes its usage consistent with other ones,
such as `CCACHE_DIR` and `CCACHE_NOHASHDIR`.

.cirrus.yml

@@ -4,7 +4,7 @@ env:  # Global defaults
   MAKEJOBS: "-j10"
   TEST_RUNNER_PORT_MIN: "14000"  # Must be larger than 12321, which is used for the http cache. See https://cirrus-ci.org/guide/writing-tasks/#http-cache
   CI_FAILFAST_TEST_LEAVE_DANGLING: "1"  # Cirrus CI does not care about dangling process and setting this variable avoids killing the CI script itself on error
-  CCACHE_SIZE: "200M"
+  CCACHE_MAXSIZE: "200M"
   CCACHE_DIR: "/tmp/ccache_dir"
   CCACHE_NOHASHDIR: "1"  # Debug info might contain a stale path if the build dir changes, but this is fine
 
@@ -170,7 +170,7 @@ task:
   build_script:
     - '%x64_NATIVE_TOOLS%'
     - cd %CIRRUS_WORKING_DIR%
-    - ccache --zero-stats --max-size=%CCACHE_SIZE%
+    - ccache --zero-stats
     - python build_msvc\msvc-autogen.py
     - msbuild build_msvc\bitcoin.sln -property:CLToolExe=%WRAPPED_CL%;UseMultiToolTask=true;Configuration=Release -maxCpuCount -verbosity:minimal -noLogo
     - ccache --show-stats

ci/test/00_setup_env.sh

@@ -54,7 +54,7 @@ export RUN_FUZZ_TESTS=${RUN_FUZZ_TESTS:-false}
 export BOOST_TEST_RANDOM=${BOOST_TEST_RANDOM:-1}
 # See man 7 debconf
 export DEBIAN_FRONTEND=noninteractive
-export CCACHE_SIZE=${CCACHE_SIZE:-100M}
+export CCACHE_MAXSIZE=${CCACHE_MAXSIZE:-100M}
 export CCACHE_TEMPDIR=${CCACHE_TEMPDIR:-/tmp/.ccache-temp}
 export CCACHE_COMPRESS=${CCACHE_COMPRESS:-1}
 # The cache dir.

ci/test/00_setup_env_mac_native_arm64.sh

@@ -13,6 +13,6 @@ export BITCOIN_CONFIG="--with-gui --with-miniupnpc --with-natpmp --enable-reduce
 export CI_OS_NAME="macos"
 export NO_DEPENDS=1
 export OSX_SDK=""
-export CCACHE_SIZE=300M
+export CCACHE_MAXSIZE=300M
 export RUN_FUZZ_TESTS=true
 export FUZZ_TESTS_CONFIG="--exclude banman"  # https://github.com/bitcoin/bitcoin/issues/27924

ci/test/00_setup_env_native_fuzz.sh

@@ -16,4 +16,4 @@ export RUN_FUZZ_TESTS=true
 export GOAL="install"
 export BITCOIN_CONFIG="--enable-fuzz --with-sanitizers=fuzzer,address,undefined,float-divide-by-zero,integer \
 CC='clang-16 -ftrivial-auto-var-init=pattern' CXX='clang++-16 -ftrivial-auto-var-init=pattern'"
-export CCACHE_SIZE=200M
+export CCACHE_MAXSIZE=200M

ci/test/00_setup_env_native_fuzz_with_msan.sh

@@ -22,4 +22,4 @@ export USE_MEMORY_SANITIZER="true"
 export RUN_UNIT_TESTS="false"
 export RUN_FUNCTIONAL_TESTS="false"
 export RUN_FUZZ_TESTS=true
-export CCACHE_SIZE=250M
+export CCACHE_MAXSIZE=250M

ci/test/00_setup_env_native_fuzz_with_valgrind.sh

@@ -17,4 +17,4 @@ export FUZZ_TESTS_CONFIG="--valgrind"
 export GOAL="install"
 # Temporarily pin dwarf 4, until using Valgrind 3.20 or later
 export BITCOIN_CONFIG="--enable-fuzz --with-sanitizers=fuzzer CC='clang -gdwarf-4' CXX='clang++ -gdwarf-4'"
-export CCACHE_SIZE=200M
+export CCACHE_MAXSIZE=200M

ci/test/00_setup_env_native_msan.sh

@@ -20,4 +20,4 @@ export GOAL="install"
 export BITCOIN_CONFIG="--with-sanitizers=memory --disable-hardening --with-asm=no CFLAGS='${MSAN_FLAGS}' CXXFLAGS='${MSAN_AND_LIBCXX_FLAGS}'"
 export USE_MEMORY_SANITIZER="true"
 export RUN_FUNCTIONAL_TESTS="false"
-export CCACHE_SIZE=250M
+export CCACHE_MAXSIZE=250M

ci/test/00_setup_env_native_tidy.sh

@@ -16,4 +16,4 @@ export RUN_FUZZ_TESTS=false
 export RUN_TIDY=true
 export GOAL="install"
 export BITCOIN_CONFIG="CC=clang-16 CXX=clang++-16 --with-incompatible-bdb --disable-hardening CFLAGS='-O0 -g0' CXXFLAGS='-O0 -g0 -I/usr/lib/llvm-16/lib/clang/16/include'"
-export CCACHE_SIZE=200M
+export CCACHE_MAXSIZE=200M

ci/test/06_script_b.sh

@@ -75,7 +75,7 @@ if [ -z "$NO_WERROR" ]; then
   BITCOIN_CONFIG_ALL="${BITCOIN_CONFIG_ALL} --enable-werror"
 fi
 
-ccache --zero-stats --max-size="${CCACHE_SIZE}"
+ccache --zero-stats
 PRINT_CCACHE_STATISTICS="ccache --version | head -n 1 && ccache --show-stats"
 
 if [ -n "$ANDROID_TOOLS_URL" ]; then