core: Fix crash when running dry

[zecke]

The tls variable for out_flush_params is not initialized as the flb_start function is not called during the dry run. Call flb_init directly and then shutdown the engine.

configuration test is successful
================================================================= ==63633==ERROR: AddressSanitizer: attempting free on address which was not malloc()-ed: 0x0001f71b3ac0 in thread T0
    #0 0x103c9f260 in wrap_free+0x98 (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x53260)
    #1 0x100179d9c in flb_free flb_mem.h:127
    #2 0x10017f4a0 in flb_output_exit flb_output.c:481
    #3 0x1001cb038 in flb_engine_shutdown flb_engine.c:1119
    #4 0x10010d45c in flb_destroy flb_lib.c:240
    #5 0x100008c40 in flb_main fluent-bit.c:1348
    #6 0x10000c644 in main fluent-bit.c:1456
    #7 0x18f11e0dc  (<unknown module>)

frame #6: 0x000000010017f4a4 fluent-bit`flb_output_exit(config=0x0000000102b00200) at flb_output.c:481:9
   478
   479 	    params = FLB_TLS_GET(out_flush_params);
   480 	    if (params) {
-> 481 	        flb_free(params);
   482 	    }
   483 	}

Executing fluent-bit -D crashes on macos.

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Testing
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• [ N/A] Example configuration file for the change
• [ x] Debug log output from testing the change

• [ N/A] Attached Valgrind output that shows no leaks or memory corruption was found

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• [N/A ] Run local packaging test showing all targets (including any new ones) build.
• [N/A] Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• [ N/A] Documentation required for this feature

Backporting

• Backport to latest stable release.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[zecke]

This could fix #8698 and #7283