Consistently generate build tags metadata

Dockerfile receives a minor tweak for proper output.

BuildTags value is expected as a plain `value,value,value` string,
however the current approach wraps quotes inside of quotes, and the
resulting string is `'value,value,value'` which gets escaped a
few more times (unnecessarily).

Additionally, Makefile receives a minor tweak for everyone who
builds directly.

With Make 4.3+, the empty whitespace does not seem to work as
originally intended. This causes build tags to be "netgo ledger,"
on Ubuntu 22.04 and other systems that include the newer Make
version. The build tags were intended as "netgo,ledger" which
can be observed on Make 4.2 (shipped with Ubuntu 20.04).

This change swaps out the `+=` use in favor of an explicit `:=`.
Ref: https://www.gnu.org/software/make/manual/html_node/Appending.html

Upstream: cosmos/gaia@297cdb9

CHANGELOG.md

@@ -40,6 +40,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Misc Improvements
+
+  * [#XXX](https://github.com/osmosis-labs/osmosis/pull/XXX) Consistently generate build tags metadata, to return a comma-separated list without stray quotes. This affects the output from `version` CLI subcommand and server info API calls.
+
 ## v15.0.0
 
 This release containts the following new modules:

Dockerfile

@@ -46,7 +46,7 @@ RUN --mount=type=cache,target=/root/.cache/go-build \
             -X github.com/cosmos/cosmos-sdk/version.AppName="osmosisd" \
             -X github.com/cosmos/cosmos-sdk/version.Version=${GIT_VERSION} \
             -X github.com/cosmos/cosmos-sdk/version.Commit=${GIT_COMMIT} \
-            -X github.com/cosmos/cosmos-sdk/version.BuildTags='netgo,ledger,muslc' \
+            -X github.com/cosmos/cosmos-sdk/version.BuildTags=netgo,ledger,muslc \
             -w -s -linkmode=external -extldflags '-Wl,-z,muldefs -static'" \
         -trimpath \
         -o /osmosis/build/osmosisd \

Makefile

@@ -50,7 +50,7 @@ build_tags += $(BUILD_TAGS)
 build_tags := $(strip $(build_tags))
 
 whitespace :=
-whitespace += $(whitespace)
+whitespace := $(whitespace) $(whitespace)
 comma := ,
 build_tags_comma_sep := $(subst $(whitespace),$(comma),$(build_tags))