Merge some layers and use inline chmod to reduce image size and layers

[stklcode]

• merge consecutive RUN statements, if the belong to the same feature
• clear apt cache after each setup step
• use inline --chmod for COPY steps

This reduces the final image by 9 layers and about 20MB compressed size withuht functional changes.

---

Comparison of docker history for both images:

CREATED BY	ID (orig)	SIZE (orig)	ID (red)	SIZE (red)
/bin/sh -c #(nop) EXPOSE 80 443	e30dd53c1f1b	0B	2133ebe85ced	0B
/bin/sh -c #(nop) CMD ["/usr/bin/openxpkic...	<missing>	0B	<missing>	0B
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	<missing>	5.63kB	<missing>	5.62 kB
/bin/sh -c #(nop) VOLUME /var/www/download	953dadccae04	0B	ae515104e03d	0B
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	<missing>	3.07kB	<missing>	3.07kB
/bin/sh -c #(nop) WORKDIR /var/log/	be42f81f25d3	0B	905974a1fcef	0B
/bin/sh -c #(nop) VOLUME /var/log/openxpki...	<missing>	0B	<missing>	0B
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	<missing>	2.56kB	<missing>	2.56kB
/bin/sh -c #(nop) VOLUME /run/openxpkid /r...	32724467e995	0B	95ea01205edb	0B
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	<missing>	2.56kB	<missing>	2.56kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	9c65b1199618	2.56kB	--	--
/bin/sh -c #(nop) COPY file:f46f91712095eb...	f43959311425	3.07kB	394a3134038f	3.07kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	a627406079e2	2.56kB	--	--
/bin/sh -c #(nop) COPY file:67974057a5b181...	86315ec6a47d	6.14kB	da5836cc73ed	6.14kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	0c8c8736064d	2.56kB	--	--
/bin/sh -c #(nop) COPY file:be239d5e97f3ec...	e08636d9989a	7.17kB	eefe7fe71951	7.17kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	fba788433710	4.1kB	--	--
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	59527cfd1a1b	4.1kB	--	--
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	7fd44c1d4435	3.58kB	445666cf8208	6.66 kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	fd7dbc552bfa	4.1kB	--	--
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	15ba2c8dd4b7	13.8kB	--	--
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	d6fb34b9af93	17.4kB	e1340e83fc0f	28.2 kB
/bin/sh -c #(nop) VOLUME /etc/openxpki	8a6a75224d70	0B	90b00a93890c	0B
/bin/sh -c #(nop) ENV LANG=en_US.UTF-8 LAN...	<missing>	0B	<missing>	0B
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	<missing>	50.7kB	<missing>	50.7 kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	eaffeb09325a	9.22kB	7c790b466b76	9.22 kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	147d29c28b97	8.7kB	--	--
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	439f7cd543e2	5.12kB	--	--
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	079c7928d947	378MB	745ea78437b3	378 MB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	268e363b50db	5.12kB	9784a6bb4de1	5.12 kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	31574b1184b9	4.1kB	e2522367dd82	4.1 kB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	d0f49c13702b	5.21MB	074f07eef666	5.21 MB
|2 DEBIAN_FRONTEND=noninteractive OPENXPKI...	53af8ba62add	202MB	c28873d198ba	182 MB
/bin/sh -c #(nop) ARG DEBIAN_FRONTEND OPEN...	b3a422523a11	0B	b3a422523a11	0B
/bin/sh -c #(nop) ARG DEBIAN_FRONTEND	<missing>	0B	<missing>	0B
# debian.sh --arch 'amd64' out/ 'bookworm'...	<missing>	121MB	<missing>	121MB

Comparison of compressed size reported by docker images:

REPOSITORY	TAG	IMAGE ID	SIZE
localhost/openxpki	reduced	7e681aa6f2f3	687 MB
localhost/openxpki	original	cbd901c12d87	707 MB

(* actually built and tested with podman, but the results should be equally valid)