Modify FFI client methods to avoid task spawning #594

Job	Run time
bindings-macos (macos-14, aarch64-apple-darwin)	2m 30s
features (--no-default-features)	1m 45s
bindings-macos (macos-13, x86_64-apple-darwin)	4m 52s
bindings-windows (x86_64-pc-windows-msvc, true)	7m 43s
documentation	3m 10s
features (--no-default-features --features serial)	1m 48s
bindings-windows (i686-pc-windows-msvc, false)	3m 59s
features (--no-default-features --features tls)	2m 4s
ffi-cross (x86_64-unknown-linux-gnu)	2m 32s
guide	1m 11s
ffi-cross (x86_64-unknown-linux-musl)	2m 52s
linting (stable)	49s
test (ubuntu-latest, stable)	1m 6s
ffi-cross (arm-unknown-linux-gnueabihf)	2m 39s
linting (beta)	48s
test (ubuntu-latest, beta)	1m 4s
ffi-cross (arm-unknown-linux-musleabihf)	2m 53s
test (windows-latest, stable)	2m 40s
ffi-cross (aarch64-unknown-linux-gnu)	2m 37s
test (windows-latest, beta)	2m 42s
ffi-cross (aarch64-unknown-linux-musl)	2m 45s
ffi-cross (armv7-unknown-linux-gnueabihf)	2m 35s
ffi-cross (arm-unknown-linux-gnueabi)	2m 42s
packaging	0s
release	0s
	59m 46s

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