treewide: remove redundant quotes

nixos/modules/config/malloc.nix

@@ -6,7 +6,7 @@ let
 
   # The set of alternative malloc(3) providers.
   providers = {
-    "graphene-hardened" = rec {
+    graphene-hardened = rec {
       libPath = "${pkgs.graphene-hardened-malloc}/lib/libhardened_malloc.so";
       description = ''
         An allocator designed to mitigate memory corruption attacks, such as
@@ -14,7 +14,7 @@ let
       '';
     };
 
-    "jemalloc" = {
+    jemalloc = {
       libPath = "${pkgs.jemalloc}/lib/libjemalloc.so";
       description = ''
         A general purpose allocator that emphasizes fragmentation avoidance
@@ -22,7 +22,7 @@ let
       '';
     };
 
-    "scudo" = {
+    scudo = {
       libPath = "${pkgs.llvmPackages.compiler-rt}/lib/linux/libclang_rt.scudo-x86_64.so";
       description = ''
         A user-mode allocator based on LLVM Sanitizer’s CombinedAllocator,
@@ -32,7 +32,7 @@ let
     };
   };
 
-  providerConf = providers."${cfg.provider}";
+  providerConf = providers.${cfg.provider};
 
   # An output that contains only the shared library, to avoid
   # needlessly bloating the system closure